A: The built-in backup program in your iMacs, called Time Machine, doesn’t require Apple’s Time Capsule product to work. It will work with almost any brand of directly connected external hard disk.

For instance, I back up my home iMac to a Western Digital drive that’s connected to it via a cable.

As for hard-drive life, it’s my experience that many seem to die sooner or later, especially if they are used heavily. I don’t know if the ones inside the Time Capsule are especially fragile. But, in just the past six months, I’ve had an external hard disk from G-Tech die on me; seen an internal hard disk on my home Dell die for a second time; and discovered that the hard disk on my colleague’s MacBook died.

One way to protect against the failure of a local backup drive is to consider, in addition to using an external disk, backing up your data to an online backup service like Mozy, Carbonite or SugarSync.

My Dell has Microsoft Vista but I can upgrade free to the new Windows 7. However, I was told my antivirus software won’t be compatible and my email will change—the program will no longer be “Windows Mail.” What do you recommend?

A: I regard Windows 7 as much better than Vista, but you are correct that many antivirus programs will require upgrading and Windows Mail will go away during the upgrade. You’ll have to install a new email program, such as the very similar “Windows Live Mail,” which can import your messages. So, the question really is one of trade-offs. If you’re satisfied with Vista, and would rather not perform these program replacements, you should stand pat. If you don’t like Vista, and are anxious to replace it, then the hassles you describe could be worth it.

Will Office 2003 work with the new Windows 7 operating system?

A: Microsoft, which makes both products, says the answer is yes, though I haven’t tested it.

Is it possible that the Verizon Motorola Droid, which doesn’t work in Europe, could be turned into a “world phone” that could work on European cellphone networks via an app somebody might develop?

A: An app wouldn’t be able to do that for the current Verizon Droid. It’s a hardware issue.

Verizon’s Droid, like most Verizon phones, is built to run on a type of network called CDMA that isn’t used in Europe or most other countries outside the U.S., which use a network standard called GSM.

To run on these networks, the Droid, or any other current CDMA phone, would need an entirely different radio, or two radios, one for each type of network.

Verizon offers a handful of so-called “world phones,” which have both kinds of radios inside, but the Droid isn’t one of them. Motorola may well make a new model with two radios, or even a model with one radio that would work overseas, and I wouldn’t be surprised if it did so.

What could be done with an app is to allow the Droid to make so-called VOIP phone calls via the Internet.

In fact, while I haven’t checked, there may already be such an app for Android—the Droid’s operating system—that would do so. But, in many cases, making such Internet phone calls requires the user to be in range of a Wi-Fi network. Some carriers don’t allow such calls to be made over their cellular networks.

You can find Mossberg’s Mailbox, and my other columns, online for free at the All Things Digital Web site, http://walt.allthingsd.com.

To avoid the difficulties you described last week with migrating from Windows XP to Windows 7, what do you think about a two-step approach whereby we buy Vista, upgrade from XP to Vista, and then go from Vista to Windows 7?

That would work, since–unlike those running XP–PCs running Vista can be upgraded to Windows 7 directly, without wiping their hard drives, displacing any files or re-installing any programs.

However, you’d be doing twice the work and paying for two new versions of Windows instead of one.

If I bought a Vista computer, but had it downgraded at the factory to XP, will my situation be any different than what you described should I choose to migrate to Windows 7?

According to Microsoft, the answer is no. Your computer is now a Windows XP computer, and thus still has no direct upgrade path to Windows 7. You would still have to remove and later restore your personal files, wipe your hard disk clean, and then re-install all your programs. However, if you received Windows Vista installation disks with the machine, you could upgrade it to Windows Vista first, and then, upgrade it directly to Windows 7, a process that doesn’t require any of those cumbersome steps.

Does the difficult scenario of moving from Windows XP to Windows 7 that you described last week also apply to those of us who run XP on Macs in virtual-machine programs like Parallels or Fusion?

Yes. Microsoft says the same migration steps are necessary whether the Windows XP computer is physical or virtual, and that includes Macs running XP via the Parallels or Fusion software.

It also applies if you are running XP on a Mac using Apple’s Boot Camp program and wish to move to Windows 7.

After Windows 7 comes out in October, will Microsoft somehow force us XP users to stop using it? Is there any reason I have to upgrade, or can I keep using XP, which meets my needs perfectly?

You can keep using Windows XP and all your current programs on your current computer. It won’t suddenly expire.

Especially in light of how hard it will be to upgrade, can you please explain what advantages Windows 7 will have over XP, which is tried and true? I deliberately skipped Vista and am inclined to skip this new Windows version as well.

People should never feel stampeded to upgrade their technology and should keep using whatever meets their needs and makes them comfortable.

However, based on my testing of pre-release versions of Windows 7, I would say it is significantly better than XP, which, after all, was designed a decade ago, an eternity in computer time.

I’ll cite just a few examples. Microsoft says that Windows 7 is more secure than XP, because its underlying architecture allows more defenses against malicious software than in the older product. Microsoft claims, and my tests bear out, that Windows 7 makes networking computers much simpler, quicker and more reliable than XP does. And the company says that Wi-Fi networks work better and faster than they do with XP.

I would add that, if Windows 7 catches on in a way that Vista didn’t, you may gradually find that new software and hardware makers will stop bothering to make their products compatible with XP, though this process will take years.

You can find Mossberg’s Mailbox, and my other columns, online for free at the All Things Digital Web site, http://walt.allthingsd.com.

In your spring buyer’s guide, you wrote that adequate graphics chips will be more important than ever, but in the past you’ve advised that memory, or RAM, was key to speed and performance. Can you now get the same gains by buying or adding a better graphics chip? Or is RAM just as important as ever?

There are lots of things that can improve the performance of a PC or Mac. But adding memory still gives you more bang for the buck than any other, in my view. What I was saying last week is that the forthcoming Microsoft and Apple operating systems will be relying more on graphics chips to help take some of the load off the main processor and speed up certain tasks. Even so, a better graphics chip isn’t a substitute for more main memory. In fact, most moderately priced computers use so-called integrated graphics chips, which lack dedicated memory and share some of the computer’s main RAM. So having plenty of main memory is directly related to getting the most out of such graphics chips.

Can the iPhone be connected to desktop peripherals? I want to be able to plug my iPhone into a large monitor and printer.

There are already several apps, including one from Hewlett-Packard, that allow you to print photos wirelessly from an iPhone to a printer that’s connected to a Wi-Fi network. But, as far as I know, there is nothing on the market today that can connect an iPhone to an external monitor or keyboard, or to a printer for nonphoto printing. However, Apple has announced that the new 3.0 version of the iPhone operating system, due this summer, will enhance the ability of the iPhone to work with add-on hardware, either via cables or wirelessly. The company showed this off with medical devices, but it’s possible that some third party could make it work with monitors or printers or keyboards.

A recent article in the Journal reported that a person had installed the Mac operating system on a Windows laptop. Is this really possible and is it legal?

Apple doesn’t sell or license its Mac OS X operating system for use on non-Apple hardware. In fact, the company considers it illegal to install OS X on other brands of computers. Nor does it produce OS X drivers for non-Apple hardware features that are built into competitors’ computers. Nevertheless, some computer hobbyists have installed OS X on non-Apple hardware, and posted photos and videos online to prove it.

Even if you are willing to ignore the legal issues, this process, while not brain surgery, takes more skill than the average user possesses. And, in the end, some features of the computer may wind up disabled or require workarounds to function. For instance, on one such machine I saw, the speaker port didn’t work with the Mac OS.

• You can find Mossberg’s Mailbox, and my other columns, online free of charge at the new All Things Digital Web site, http://walt.allthingsd.com.

I am utterly fascinated with the iPhone. Dying to get one. I’ve been a Verizon Wireless person for 15 years and have never had a coverage problem in the metro Boston area. I don’t hear great things about AT&T’s 3G. Do you think it’s worth the switch?

While I believe the iPhone is a marvelous device, I have always advised that nobody should get any phone unless it is on a network that they are sure works to their satisfaction in the areas where they will use it. Personally, I find AT&T’s network adequate where I use it, and getting better, so I am happy with my iPhone. But there are many others who have either given up their iPhones out of frustration with AT&T, or who have decided against buying one because they prefer another carrier, or want to avoid AT&T.

So, my advice is to ask friends around Boston who have iPhones or other AT&T 3G devices how they feel about the network. You might also enter your ZIP Code at some Web sites that track overall carrier coverage and dead zones, like cellreception.com, or deadcellzones.com.

If this research suggests you should avoid AT&T, but you are still “dying” for an iPhone, you might consider the iPod Touch, which is essentially an iPhone without the cellphone inside. It lacks the iPhone’s camera, GPS and built-in microphone, but it does connect to the Internet via Wi-Fi and runs the vast majority of iPhone apps. It doesn’t carry any monthly fee or require a carrier contract.

How do I forward an email from Gmail? I don’t see any icon for forwarding messages like I do on other email programs.

Gmail hides a bunch of menu choices under the Reply icon in the upper-right-hand corner of open emails. If you click on the small downward arrow next to the Reply icon, you will see more actions you can take on the message, including Forward, Reply to All, Print and others.

I read your recent article on IE8 and installed it on my desktop. I did not notice in your article any mention of IE8 slowing the computer down significantly, but it has had this effect on my PC. Why didn’t you mention it? Can I uninstall IE8 and return to the prior version?

I didn’t mention the problem you are having because I never observed that Internet Explorer 8 caused any general slowdown of any of the multiple Windows PCs on which I tested it. I did warn that IE8 itself grew sluggish when it had a large number of Web sites open simultaneously in tabs, but, in my tests, even that didn’t slow down the whole computer.

However, you can indeed uninstall IE8 and return to the previous version. Microsoft has provided complete instructions, and even an automated uninstall program, at: support.microsoft.com/kb/957700.

• You can find Mossberg’s Mailbox, and my other columns, online free of charge at the new All Things Digital Web site, http://walt.allthingsd.com.

I have a laptop that I use primarily to play music. Is there any way to disable its connection to a wireless network?

Sure, but exactly how you do that depends on the laptop’s hardware and operating system. Some Windows laptops have a hardware switch, or a keyboard function — often identified by some sort of transmitter icon — that turns the Wi-Fi wireless radio inside off. If yours does, just use these hardware controls to kill Wi-Fi.

Others require disabling Wi-Fi via software. In Windows XP, go to the Network Connections control panel, find the Wi-Fi connection, right-click on that icon, and select “Disable.” In Windows Vista, go to the Network and Sharing Center control panel, locate the wireless network, and click the “Disconnect” command in the information area under its name. On a Mac laptop, you can just click on the fan-like Wi-Fi symbol in the menu bar and select “Turn Airport Off” (”Airport” is Apple’s term for its Wi-Fi radio).

If your Windows laptop uses an application other than control panels to manage your Wi-Fi connections, you may have to disable them from within that program.

Thanks for your column on netbooks. Which of the netbooks came pre-installed with Microsoft Office? For those that didn’t, how can you install Microsoft Office onto the device?

I tested only four models, all running Windows XP. None came with a full, activated version of Office installed. Two — the Acer Aspire One and the MSI Wind U100 — came with trial versions of Office pre-installed. Another, the Asus Eee 1000H, came with an alternative office suite, StarOffice. Two, the Asus and the MSI, came with a stripped-down office suite, Microsoft Works.

The simplest way to install Office, or any other software that comes on disc, onto a netbook is to plug in an external DVD drive using a USB port.

I have two questions about the iPhone. My first question is whether or not it’s possible to tether the phone to a computer for use as a modem. My second question is whether it’s possible to rent or buy movies on the phone itself or if that needs to be done from a laptop or desktop?

It isn’t currently possible to use the iPhone as a tethered modem, but AT&T recently said that functionality might be coming. It also isn’t possible to buy or rent movies directly on the phone, only music. You have to transfer movies from a computer.

• You can find Mossberg’s Mailbox, and my other columns, online free of charge at the new All Things Digital Web site, http://walt.allthingsd.com.

Should I install Microsoft’s “SP3″ upgrade to Windows XP? I hear opinions on both sides.

In general, I recommend this upgrade, officially called Service Pack 3, because it beefs up security, and that helps not only you, but all Windows users, to avoid the spread of malicious software. If your PC is more secure, it is less likely to be used as a source from which other PCs can be infected.

I have upgraded a couple of XP PCs to SP3 without any downside. However, like you, I have also heard from some users that the upgrade caused them problems.

As with any major operating-system upgrade, either outcome can occur, depending upon your computer’s particular configuration and condition. So, if you’re on the fence, consider your level of concern about security.

How do cellular data cards compare with fast cable modems in terms of Internet speed? Are these cards more secure than Wi-Fi?

In my experience, using and testing cellular data cards on various laptops, they typically deliver, in real day-to-day use, somewhere between 300 kilobits per second and 1.5 megabits per second. By contrast, a fast cable Internet service can actually deliver up to 16 mbps. So cable is much faster.

Your security question is much more complicated. Wi-Fi security can range from very poor to quite good. It depends on where and how you use Wi-Fi, how you or others have set up the wireless network, and how you have configured your own computer.

Accessing the Internet over a cellular network is a more controlled process, because the cellphone-network operator manages the transmission, and in most cases supplies and configures the software on your computer. So, it is likely to be safer than the worst Wi-Fi setups. But I would never suggest that cellular data card transmissions are invulnerable to hackers or criminals.

What’s the difference between file-based backup and image-based backup software? Why would I choose one over the other?

Image-based backup software copies an image of your entire hard-disk, including all the programs, settings and obscure files that you never see. While it can be used to recover individual files, in some cases, it is mainly designed to allow you to restore your entire hard disk in the event that you lose it all.

File-based backup software, which is more common among consumers, is typically designed to preserve a copy of only your personal data, the material you can’t re-purchase or re-install if your hard disk dies.

That includes word-processing files, spreadsheets, presentations, emails, contacts, calendar items, photos and other items you created. It also is often used to back up music and video files that would be time-consuming, or very expensive, to re-acquire. And in some cases, it can preserve settings and preferences, such as Web bookmarks.

Both types of backup generally begin with a time-consuming initial session, followed by shorter sessions to update the backup with incremental changes.

Many people choose file-based backup because it occupies less space, and is generally quicker and also less expensive. Image-based backup is for folks who are willing to spend the added money and time to be sure they can restore their whole computer, or clone its contents completely to another machine.

• You can find Mossberg’s Mailbox, and my other columns, online free of charge at the new All Things Digital Web site, http://walt.allthingsd.com.

At work I am told to turn off my desktop PC at the end of the day. My wife’s office tells her to leave her computer on overnight. My former employer said to turn off the monitor but leave the PC on. What’s right?

Given the energy, environmental and economic crises, my view is that you should completely shut down both your computer and your monitor any time they will be unused for more than a few hours. And, of course, you should set them to go into sleep mode after they are idle for far less time than that. To be honest, I myself am not always faithful to that advice, but I am resolved to get better at it.

Of course, there are some nuances to the issue of overnight shutdowns. If you, or your company, routinely perform important operations overnight, like backups or security scans or system tune-ups, then you have to leave the computer on, but you should still turn off the monitor.

How much memory do you recommend for a new computer running Vista Home Premium?

Two gigabytes minimum, and three gigabytes if your budget can handle it. The latter is roughly the maximum that popular consumer versions of Vista (called 32-bit versions) can use.

For smooth, quick operation in common tasks, it’s been my experience that Vista demands more memory than either Windows XP or Apple’s Leopard operating system. And the need for added memory rises if your PC uses “shared” video memory, which means your graphics system lacks its own dedicated memory and relies on draining the main memory. This arrangement is common in less expensive computers.

We are planning a trip to the British Isles this summer with a side trip to Brussels. We plan to bring our iPhone on the trip. What is the current situation with using European networks? Will my U.S. AT&T account just work or do I need to make pre-arrangements? I realize my iPhone won’t be able to access the faster 3G networks over there, but can I use slower networks? Being limited to Wi-Fi would be a bummer.

The iPhone 3G can indeed handle 3G networks in Europe, though the original iPhone can handle only slower networks. Both models can use Wi-Fi there.

You will need to call AT&T before you leave, though, and “provision,” or set up, your account, for international roaming. Note that such roaming is expensive, with very high rates for both voice use and data use. AT&T has some monthly add-on plans that cut these fees, but, if I were you, I would turn off data roaming until and unless I needed it; do most email and Web surfing via Wi-Fi; and consider downloading Truphone, a voice-calling program that uses Wi-Fi instead of cellphone networks.

You can find Mossberg’s Mailbox, and my other columns, online free of charge at the new All Things Digital Web site, http://walt.allthingsd.com.

I am in the market for a new HDTV and the newspaper ads are using terminology that I’m unfamiliar with. Do TVs rated at “720p” provide the same quality picture as those rated at “1080p”?

Technically, the answer is no, but it may not matter. The 1080p resolution is certainly higher, but almost nobody can tell the difference between the same material shown in the two resolutions on TV screens up to around 50″ in size and at the typical distances from which people watch those screens. Not only that, but most sources of video content, with the exception of Blu-ray discs, can’t even fully utilize 1080p. Major TV networks don’t use it yet because it requires a lot of bandwidth.

If you can afford a set that can handle 1080p, you might want to buy it so that you are ready in case a lot of 1080p content one day becomes available. You might also want a 1080p set if you are a videophile; have an enormous screen or a projector that fills a large wall; or if you play a lot of Blu-ray discs and believe you can discern the difference on a typical-sized screen. Otherwise, you could save money by buying a 720p set and you might never know the difference.

In 2006, you recommended a powerline adapter for Internet access by Netgear, the XE104. Is this still a good buy or are there others by now that are better?

I haven’t tested powerline adapters, the gadgets that route computer networks over standard home electrical wiring, since that date. Netgear and its competitors — such as Linksys and Belkin — have, naturally, come out with newer, faster units since then. But I am still personally using the XE104 successfully and feel I continue to get my money’s worth from it. It is still being sold. The newer units typically have greater speed in order to do a better job of streaming video around a home, but they work in basically the same way.

I have a Windows XP system, and things work well with my cable modem in my office. But when I’m on the road using Wi-Fi, I can receive emails, but can’t reply or send out. Any idea on how to resolve this problem?

This usually happens because the Wi-Fi provider is blocking the outgoing email server (called an “SMTP” server) that you or your IT department has set up in your email program. Some providers block all such outgoing servers. There are a number of possible solutions. The simplest is to use a Web-based email service, like Gmail or Yahoo Mail, or the Web-based version of your usual service. If your email is provided by your company, you may be able to access a version of Microsoft Outlook over the Internet that will work.

Another possibility is to ask the provider at the hotel or airport what SMTP server it does allow — usually its own — and enter it into your email program’s settings, if you know how. Yet another option would be to use a data card from a cellphone carrier, which I have found can usually overcome this problem. There may be other workarounds, and I invite readers to suggest them.

You can find Mossberg’s Mailbox, and my other columns, online, free, at the new All Things Digital Web site, http://walt.allthingsd.com.

In your recent review of the new iPhone 3G, you mentioned that it had weaker battery life between charges than the original iPhone, but that you learned various techniques to minimize this problem. Can you elaborate?

The biggest battery drain is the fast, but power-hungry, 3G cellular network, which lessens battery life on all phones. So, when you are able to use Wi-Fi instead for data, you can turn off 3G reception using a setting Apple provides. You will still be able to make and receive voice calls over older networks that won’t drain the battery as fast. The same is true in reverse. If you are using 3G for data, turn off your Wi-Fi capability.

Apple has a Web page with many more battery-saving tips at: apple.com/batteries/iphone.html. Turning these functions on and off, and worrying about battery life, however, is a pain. So if you hate the thought of learning and using these techniques, and suspect your usage pattern might push the new iPhone’s battery to its limits, you shouldn’t buy one. At the least, you might want to wait and see if Apple can tweak its software to squeeze more battery life out of the device.

You mention in your article that the iPhone 3G’s battery is not replaceable. Does that mean that, when it can no longer hold a charge, I’ll have to replace the entire phone?

No. Apple has a battery-replacement program for iPhones. If your battery drops to below 50% of its original capacity during the one-year warranty period, the company will replace the battery at no cost. After your warranty expires, Apple will replace the battery for $86. Of course, in both cases, you will have to do without your phone for however long it takes to complete the battery replacement. More details are at: apple.com/batteries/replacements.html.

In your column, you never mentioned the iPod Touch, which I own and use for email, Web surfing and music. Can the Touch be upgraded to the new 2.0 version of the iPhone operating system, and can it use the new third-party applications?

Yes, but with some qualifications. First, while the software upgrade is free for owners of the original iPhone, it costs $10 for owners of the iPod Touch. This has to do with Apple’s interpretation of accounting rules governing the addition of new features to different types of products.

Second, while most of the new iPhone programs available from the “App store” will work fine on the Touch, some cannot because of hardware differences between the two devices. For instance, voice-recording programs won’t work on the Touch, because it has no microphone. The App store indicates which programs are compatible with which device.

Since the new iPhone 3G includes a GPS chip and a speaker, can it be used as an audible, turn by turn, in-car navigation device?

Apple didn’t build such a function into the new iPhone, but some third-party companies are rumored to be trying.

You can find Mossberg’s Mailbox, and my other columns, online, free, at the new All Things Digital Web site, http://walt.allthingsd.com.

You recently wrote that people should make sure new laptops have the new, faster “n” version of Wi-Fi built in. But how do you do that? All I see are impenetrable feature descriptions such as: “Built-in high-speed wireless LAN (802.11b/g).” I cannot understand this language.

Computer retailers too often insist on using techno-babble or engineering lingo, even when referring to frequently used terms like “Wi-Fi.” In my view, this practice is either lazy, or arrogant, or deliberately designed to confuse.

In this case, the product description you quote in your question is indeed referring to Wi-Fi when it uses the phrases “wireless LAN” and “802.11b/g.” The phrase “LAN” means “local area network,” a means for connecting computers to each other, and to the Internet. Engineers refer to Wi-Fi as “802.11″ followed by a letter like “b” or “g” or “a” or “n.” These letters refer to various flavors of Wi-Fi that have different speeds and ranges. The laptop whose description you quote doesn’t offer the “n” type of Wi-Fi, only the older “b” and “g” types.

In your column about the new Gogo service for using Wi-Fi on airplanes, you mentioned that iPhones will work with the system. But how can one do this legally, when passengers must turn off the cellular radio on phones aboard planes, and the method for doing that on iPhones also turns off the Wi-Fi function?

The solution is to use the new iPhone (AAPL) operating system version due out July 11. This version allows you to turn off the cellphone radio, while leaving the Wi-Fi radio on. It will come on all of the new 3G iPhones, and will be a free upgrade for the original iPhone models. Of course, on flights without officially approved Wi-Fi, both types of radios must be turned off on all devices.

Your June 26 Mossberg’s Mailbox explained how to export Internet Explorer (MSFT) Favorites. Please explain how to export Firefox 3.0 Bookmarks.

You go to the Bookmarks menu and select “Organize Bookmarks.” In the window that opens, select the star icon at the top and choose either “Backup” or “Export HTML.” The first choice saves your bookmarks in a new format introduced in Firefox 3.0 that preserves tags you may have added to your bookmarks. The second choice has been in prior versions of Firefox and will save your bookmarks in the same sort of format Firefox has previously used.

The file created by the “Backup” method can be imported into another copy of Firefox 3.0 by following the same steps, but choosing “Restore” and then “Choose File.” The file created by the “Export HTML” method can be imported into any version of Firefox using the Import or “Import HTML” function.

• You can find Mossberg’s Mailbox, and my other columns, online for free at the new All Things Digital web site, http://walt.allthingsd.com.