Here are a few questions about computers I’ve received recently from people like you, and my answers. I have edited and restated the questions a bit, for readability.

I switched from PC to Mac a year ago, but now I am thinking of adding a Windows laptop. If I do, what kind of compatibility problem would I have? I would be using the laptop mostly to write, to send/receive email and to Web browse.

In the old days, there were compatibility problems, but most of those have gone away. Based on your simple predicted usage, I’d say that you should be fine. For instance, both Macs and PCs can interchangeably open and edit all of the major file types — JPG pictures, MP3 music, Microsoft Office documents, Adobe PDF files, etc. Email and instant messages can, of course, be exchanged between the two platforms, even if you are using different programs. And Macs understand Windows file extensions. Also, you can use both platforms simultaneously on the same home network to access the Internet.

In some cases, you might need different programs to open the same files on the two platforms. But even that obstacle has greatly diminished. For instance, programs like the Firefox and Safari Web browsers, Adobe Reader, iTunes, Microsoft Office, Google Earth, Picasa, Photoshop and many others come in native versions for both platforms that can handle the same files. And, of course, Web-based programs like Gmail and Yahoo Mail work on both. Sometimes, the same programs have different features and user interfaces on Windows and Macs, but I haven’t found these differences hard to master.

The biggest problems for average users are Quicken, whose Mac version is inferior and incompatible; Internet Explorer, which is no longer made for the Mac; and Microsoft Outlook, which is replaced on the Mac by a program called Entourage that is similar but uses a different file format. And networking can be tricky. In general, the Mac does a better job of seeing Windows PCs on a network than Windows does of seeing Macs.

I use Outlook Express for my email, and I store a lot of mail in local folders. Is there a simple way to back these up? If I buy a new computer, can they be transferred?

Yes. There are two methods. One is a manual method, which Microsoft explains in a detailed document at this Web site: support.microsoft.com/kb/270670.

The other, quicker, method is to obtain one of several utility programs that can back up your Outlook Express data and, in some cases, allow you to transfer it to another PC. I haven’t tested these in years, and thus can’t recommend one over another. But one example is a free program called Outlook Express Backup, which can be found at genie-soft.com/products/oeb. Another is a $40 program called Outlook Express Backup Wizard, which can be found at: outlook-express-backup.com.

Do you know of an iPhone GPS application that speaks directions? It would make the iPhone similar to a TomTom or Garvin GPS unit.

A: No, but Apple recently announced that, under its new 3.0 operating system for the iPhone, such programs will be possible. Several companies are believed to be working on them, and I expect them to be available later in the year. The reason none exist yet is partly legal, having to do with the licensing of the underlying maps.

• 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 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.

Here are a few questions about computers I’ve received recently from people like you, and my answers. I have edited and restated the questions a bit, for readability.

I am going to start college in the fall and I need a laptop. Uncle Jim, who is a Mac addict, is making an argument for a MacBook with Parallels 3.0 and Windows XP installed. He said that way I would have the best of both worlds. My mom is looking at the price. She said we could get a PC for less money but I want to make sure we’re making the right decision. If money is not an issue, what is your recommendation?

Both your mom and your uncle are correct. You can indeed get a decent laptop from Dell or Hewlett-Packard for less than the $1,099 that Apple’s least expensive Mac laptop, the MacBook, costs. But, in my view, the Mac has a better, faster operating system, better built-in software, and is far less likely to expose you to viruses and other malicious software. Plus, the MacBook itself is a sturdy piece of hardware. And there’s a very good Mac version of Microsoft Office that is fully compatible with files created on the Windows version.

Your uncle is also correct that Macs can run Windows, and Windows software, quite well. However, the solution he suggests, using the Parallels software, which enables Windows use on a Mac, will add significantly to the price. Parallels costs around $60, and you also must buy a full, boxed edition of Windows XP or Vista. While prices for Windows vary, this full version (not an upgrade version) of XP can cost nearly $200, and Vista typically costs more.

So, if money really isn’t an issue, I recommend the MacBook. But, since that is rarely the case in real life, you might want to weigh the cheaper alternatives more carefully. Or, if you do buy the MacBook, I’d hold off on the Windows installation until and unless you find you need Windows programs that have no counterpart on the Mac. The average undergraduate likely won’t.

I am dissatisfied with my Internet service provider and I would like to switch to another one. If I switch, can I keep the same email address? Do I have to keep paying the old ISP if I switch and keep the email address?

It depends on your ISP. If it is America Online, you will be able to drop AOL as your ISP and continue to use your aol.com address, regardless of which provider you use to access the Internet. But, in most cases, if you are using the email address provided by your ISP, you will have to relinquish it. However, I would suggest you consider obtaining an email account that isn’t tied to an ISP, so that, if you have to change ISPs again, it won’t disrupt your email. Among such email-only services are Yahoo Mail, Microsoft’s Windows Live Hotmail, and Google’s Gmail.

Your column last week concerned a navigation device called Dash Express that transmits the speed and location of your car to the company for traffic information purposes. But couldn’t this capability also be misused by the company to track a driver’s whereabouts, or even help issue speeding tickets?

Theoretically, yes. But the company, Dash Navigation, says it retains no personally identifiable information on its servers, and merely collects traffic data from participating cars anonymously. A company spokeswoman says: “If the FBI came in and asked us to find someone, we would have no way of locating an individual car.”

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.

Here are a few questions about computers I’ve received recently from people like you, and my answers. I have edited and restated the questions a bit, for readability. This week my mailbox contained questions about switching to a Web-based email service, viewing PDF files on Macs and antivirus programs that support Windows ME.

Q: I use an email address provided by my Internet service provider and access my email using Microsoft Outlook. I would like a more portable email address that isn’t tied to any one ISP, and an email program that is independent of any particular computer. What can you suggest?

The obvious answer is a Web-based email service that has a decent Web-based interface that can be accessed from any computer. There are lots of these, including Yahoo Mail, Microsoft’s Windows Live Mail (formerly Hotmail) and Google’s Gmail. I am not a fan of Gmail, which I believe has too many quirks and too few options for users to avoid them. Windows Live Mail is promising, but my favorite among these leading services is Yahoo Mail.

Q: I am thinking of switching to Apple, but I am wondering if Macs come with free Adobe Reader software, like some Windows computers do.

No, Macs don’t include Adobe Reader, which allows the viewing of PDF documents — but they don’t need it. The Mac operating system allows you to open and create PDF documents, right out of the box, without any additional software. If you get a PDF file as an email attachment, you can just double-click it and it opens. Even better, any program running on the Mac can save almost anything as a PDF file. For instance, you can save a Web page as a PDF file that can be opened in Adobe Reader on Windows. Adobe charges money for software that does that.

However, if you prefer Adobe Reader, there is a free Mac version, very similar to the Windows version, that you can download at www.adobe.com.

Q: Do you know of any antivirus programs that are continuing to support Windows ME in their newest versions?

The latest version of Grisoft’s very good AVG Anti-Virus program still works with the ancient Windows ME operating system, according to the company’s Web site, at www.grisoft.com.

Q: Last week, in answering a question about the speakerphone function on another Windows Mobile phone, you claimed that, on the Motorola Q, a multistep software process is needed to turn on the speakerphone. But isn’t that wrong? Isn’t there a hardware button that does that?

Yes, I erred when I wrote that. I just blanked on the hardware button, which I certainly knew about, having carried a Q for a couple of weeks while testing it. We have already run a formal correction, and I hereby apologize to Motorola for implying that the process was clumsy, when it’s simple.

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Because of the volume of email I receive, I can’t routinely answer individual questions by email, or consult on individual problems or purchasing decisions. I read all questions I receive and select three each week to answer in the column.

Write to Walter S. Mossberg at mossberg@wsj.com

There’s no other major item most of us own that is as confusing, unpredictable and unreliable as our personal computers. Everybody has questions about them, and we aim to help.

Here are a few questions about computers I’ve received recently from people like you, and my answers. I have edited and restated the questions a bit, for readability. This week my mailbox contained questions about using the speakerphone on a Treo, making a BCC address line appear in email and running the Parallels desktop on a Mac.

I recently bought a Treo 700w smartphone, which runs Windows Mobile software. But I can’t figure out how to use the speakerphone feature. How do I do that?

While you are in the Treo 700w’s phone mode, you must hit the Menu soft key and then select Speakerphone, which is the top item on the menu. This is a good example of why I prefer the 700w’s nearly identical cousin, the Treo 700p, which uses the Palm operating system. On the 700p, while you are on a call, there is a big “Speakerphone” button on the screen. Just tap it with a finger and it turns on — no menus required. The need to open menus and take other extra steps is endemic in the Windows Mobile software. On some other Windows-based phones, like the Motorola Q, it is worse. On the Q, turning on the speakerphone requires you to bring up a screen listing “Profiles,” one of which is “Speakerphone.”

I know people can use a “BCC” address line when composing an email to copy the message to other people without the main recipient knowing. But in my email program, there is no BCC line. How do I make it appear?

In many email programs, you have to manually turn on the BCC address field in the email composition menu. This is usually done by selecting an option in a menu. Generally, you have to do this only once, and after that, the BCC field will appear every time you start composing an email.

You didn’t say which email program you use, but here are some examples. In Microsoft Outlook, when you are in the new-message window, go to the View menu and select “Bcc Field.” In Microsoft Outlook Express, in the new-message window, go to the View menu and select “All Headers.” In Apple Mail, while in the new-message window, go to the View menu and select “Bcc Address Field.” In Google’s Gmail, in the “Compose Mail” window, just click on “Add Bcc,” which appears above the Subject line.

Last week, you recommended a product called Parallels Desktop, which allows Windows to run on a Macintosh. I have two questions: Will it run on older, pre-Intel Macs? And will it expose my Mac files to Windows viruses?

First, I should have made it clear that Parallels Desktop (www.parallels.com) requires a newer Mac that uses Intel processors, like the iMac, the Mac mini, the MacBook and the MacBook Pro. It won’t run on older, pre-Intel Macs — any model sold before this year and some that are still for sale. Parallels takes advantage of a special feature in the Intel chips that allows its “virtual” Windows computer to run as fast as a standard Windows PC, even though it is operating inside a window on the Mac operating system. Older Macs can use a similar product, Virtual PC for Mac, from Microsoft, but it runs much more slowly.

As for viruses, the faux Windows PC created by Parallels is just as susceptible to the vast quantity of Windows viruses and spyware as any real Windows computer. So, if you use Parallels, you must install Windows security software on its virtual Windows PC. However, any viruses you get are unlikely to harm your Mac files unless you turn on a feature that allows Parallels to share folders and files in the Mac OS. That feature is turned off by default.

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Because of the volume of email I receive, I can’t routinely answer individual questions by email, or consult on individual problems or purchasing decisions. I read all questions I receive and select three each week to answer in the column.

Write to Walter S. Mossberg at mossberg@wsj.com

Corrections & Amplifications:

The speakerphone function on Motorola’s Q phone can be turned on and off with a button on the keyboard. This column described a more complicated alternate method for turning on the speakerphone, but omitted mention of the keyboard button.

Here are a few questions about computers I’ve received recently from people like you, and my answers. I have edited and restated the questions a bit, for readability. This week my mailbox contained questions about signing up for Gmail, iPod-to-computer transfers and switching your computer’s power options.

If you have a question, send it to me at mossberg@wsj.com, and I may select it to be answered here in Mossberg’s Mailbox.

Your recent article mentioned that Google’s new Google Talk instant-messaging service was available only to users of Google’s Gmail email service. But Gmail isn’t open for new sign-ups. How can I get onto Gmail?

You are correct that people can’t just sign up for Gmail from their computers. There are two ways to get a Gmail account. You can receive an invitation from an existing member to sign up. Or, Google now allows anyone to join, provided you sign up using your cellphone and its SMS, or text-messaging, feature. Instructions for doing this are at: https://www.google.com/accounts/SmsMailSignup1

I have tested this cellphone method, and found that it works fine. Once you sign up via your cellphone, you can use Gmail with your PC or Macintosh. You don’t have to keep using your cellphone. Google says it requires the cellphone signup in order to thwart spammers who might want to use automated computer programs to obtain multiple Gmail accounts and use these accounts as a platform for sending millions of spam emails.

I have my entire music library on my iPod, placed there using Apple’s iTunes software on my main PC. Now, I want to move all the music to a second computer. But the iPod doesn’t have the capability to synchronize music to a second computer, even using the Apple iTunes software. When I try, iTunes warns that it will overwrite my iPod with its own library, which, on this second computer, is empty. Is there a way to do this?

Yes. Apple did cripple iPod-to-computer transfers, in order to please the record industry, which feared the iPod might be used to copy music to the computers of people who hadn’t purchased it, either from Apple’s iTunes store or in the form of CDs. But many utility programs have been created to allow iPod-to-computer transfers.

I have tested two such programs, and found they work well. One, for Windows, is CopyPod, which costs $19.90, at copypod.ouvaton.org. The other, for the Macintosh, is iPodRip, at $15, from www.thelittleappfactory.com.

To conserve power, my monitor shuts down automatically after five minutes or so of inactivity. This is OK most of the time, but if I want to leave a photo slide show running occasionally, I’d like to be able to override this feature. Can you tell me how? I’m running Windows XP.

The simplest way is to go into the computer’s control panel and change the setting that turns off the monitor. Click on the Start button, then click on Control Panel. Then, open the panel called Power Options. (Depending on how your computer is set up, you may have to first click on the category called “Performance and Maintenance.”)

Next, on the tab called Power Schemes, change the setting for “Turn off monitor” to “Never,” or to a time period long enough for your slide show to play. Then, click “OK.” To resume your typical five-minute turnoff, just go into this control panel again and change the setting back to “After 5 mins.” If you play slide shows often enough that doing this each time would be a pain, keep the setting at a period lengthy enough to accommodate the slide shows.

If the slide show is triggered as a screen saver, rather than as a manual process, you should be able to use the Display control panel to start it after five minutes, instead of turning off the monitor, and then set the monitor to shut off, using the Power Options panel, at a later time, after the slide show has had a chance to run for a while.

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Because of the volume of e-mail I receive, I can’t routinely answer individual questions by e-mail, or consult on individual problems or purchasing decisions. I read all questions I receive and select three each week to answer in the column.

Write to Walter S. Mossberg at mossberg@wsj.com