A: Windows programs cannot be “converted” to run directly in the Mac operating system, which is called Snow Leopard. But, if you use virtualization software like Parallels or VMware fusion, and install Windows, then a Windows program like Microsoft Outlook can run simultaneously with your Mac programs. Technically, you are running it in Windows, but the two operating systems are active at the same time. With both of these virtualization products, you can even hide the entire Windows desktop, so that the Windows program you are running simply occupies a window on your Mac like any Mac program does. You don’t even notice that Windows is running.

In the case of files you created in Windows, the situation is even simpler. Most of the common types of files consumers use—including Microsoft Office documents, MP3 music files, MP4 video files, JPG picture files, text files, Adobe PDF files, and others—can be run in native Macintosh programs without conversion and without the need to run Windows programs. So you can just copy them to the Mac side and use them in Mac programs like iPhoto, iTunes, or the native Mac version of Microsoft Office, which uses the same file formats as the Windows version.

If you have an unusual or proprietary Windows file for which there isn’t an equivalent program on the Mac, you would run it in a Windows program, as described above.

If I am planning to upgrade a Windows XP machine to Windows 7, can I buy the upgrade copy of 7 or must I buy the full version?

A: According to Microsoft’s Web site, XP is one of the older versions of Windows upon which you can indeed indeed use the less expensive upgrade versions of Windows 7. The company’s online store says: “All editions of Windows XP and Windows Vista qualify you to upgrade. So, if you’re running either on your PC today, buy a package labeled ‘Upgrade’.”

I’ve been holding out (for what feels like forever) on purchasing a Netbook because I read that Apple was coming out with one. Can you tell me anything about when they might really begin selling them?

A: Apple executives have said repeatedly and emphatically that they don’t plan to offer a netbook, which is essentially a cheap, small laptop. Instead, Apple is widely believed to be working on a small slate or tablet device that would be controlled via a fingertip touch screen. This would be sort of like a larger iPhone or iPod Touch. The company hasn’t confirmed that such a product is in the works, but many analysts and Apple bloggers predict it will debut early next year.

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

A: You will begin to see more touch-screen laptops after Oct. 22, when Windows 7 comes out, because that new operating system has optional fingertip touch-screen navigation built in. In addition, many of the major Windows PC makers are adding their own touch-navigation systems to newer models.

However, I’d offer two caveats. First, not every touch screen will be capable of performing all the multitouch actions and gestures Windows 7 will offer. Some are more limited in their capabilities.

Second, the hardware makers will likely be cautious at first about adding fully capable touch screens to all or most of their laptops.

This is partly because these screens can add significant cost in a price-conscious market, and partly because nobody is certain how popular touch-screen navigation will be on laptops as opposed to, say, on all-in-one desktops where reaching for the screen is more obvious and natural.

I have an Apple iMac, and an Apple iPhone with around 122 apps. My question is, why don’t these iPhone apps work on the iMac? Both units use the same operating system, so why not?

A: While the iPhone and the iMac each use a version of the same operating system, Apple’s OS X, they aren’t the same operating systems. The version on the iPhone is stripped down, and has been modified to support an entirely different user interface, navigation system and set of hardware capabilities.

So there are two separate collections of apps, or programs, that run on the two platforms.

I am currently running Windows Vista Ultimate on my Dell PC. I have regretted it ever since I upgraded from XP because of its terribly slow performance. I have heard good things about Windows 7 but I am afraid I will have to buy the more expensive Ultimate upgrade (which I don’t really need) instead of an upgrade to Home Premium or Professional. Is that true?

A: According to Microsoft, owners of Vista Ultimate can only perform an “in-place upgrade” to Windows 7 Ultimate, not to lesser versions. An “in-place upgrade” is the type most people think of, the type where all your programs and files and settings are preserved just as they were, but you emerge with the new operating system.

Even then, you must be careful to buy the edition of Ultimate that matches the type of architecture your machine possesses, either 32-bit or 64-bit.

However, you can downgrade to the Home Premium or Professional versions of Windows 7, if you are willing to do a lot more work, by opting for what Microsoft calls a “custom installation,” something commonly known as a “clean install.” This typically means, first, backing up all your files and settings to an external hard disk, then allowing the Windows 7 installation disk to wipe your hard disk clean before installing your preferred version of Windows 7.

You would then copy back all your files. But you cannot do the same with your programs. For these, you would have to reinstall every one, from their original disks or downloaded installation files, and then download and re-install all the patches and program upgrades that have been issued by their makers since you acquired them.

You can find Mossberg’s Mailbox, and my other columns, online for free at the All Things Digital Web site,

http://walt.allthingsd.com.

There are lots of reliable online sellers of laptops, and online buying is fine, provided you have somehow handled the machine and are familiar enough with it to be sure it’s the one you (or, in this case, your lucky wife) will be happy owning. In the case of Apple, a company whose products are rarely deeply discounted by third-party sellers, it often makes sense for online buyers to use the company’s own online store, at store.apple.com. I have found Apple’s online store to be easy to use, secure and reliable. And you get some minor benefits at the physical Apple stores if you buy directly from Apple.

However, other major online sellers with equally good reputations also carry Macs, and some do shave the prices. One good example I have used happily is amazon.com, which carries the latest MacBook Pros at discounts ranging from $5 to over $100, depending on model.

How can I set parental controls in Firefox?

The Firefox Web browser doesn’t have built-in parental controls. Its maker, Mozilla, notes that version 3.0 or later of the browser does support some of the parental-control features included in Windows Vista. But if you don’t have Vista, or want different controls, there are some add-ons for Firefox that provide these.

Among the ones Mozilla suggests using are Glubble for Families, and ProCon Latte. More information is at: support.mozilla.com/en-US/kb/Parental+controls.

In your recent Firefox review, you said Internet Explorer has a private browsing mode that doesn’t record your history or tracks while surfing. But I can’t find how to turn it on.

The feature, which is called InPrivate Browsing, is only available in the latest version of IE, called IE8. You turn it on by either selecting that option from the Safety button at the upper right, or from the Tools menu in the Menu Bar if you have chosen to make that bar visible. Once you do, an “InPrivate” label appears at the top left corner of the browser and a page appears explaining that the browser won’t record on your own PC certain records of what you do in that browsing session. There’s an additional privacy mode, available from the same two drop-down menus, called “InPrivate Filtering,” which goes further. It blocks Web sites you go to from saving certain records of your presence there on their own servers. InPrivate browsing lasts until you close the InPrivate browsing window.

When you reviewed the latest Safari Web browser awhile back, you complained that Apple had repositioned the tabs in a way that made them harder to see. A friend said that’s no longer true. Is he right?

Yes. After getting a lot of negative reaction, Apple changed Safari 4’s design so the tabs are displayed in the previous manner, below the toolbar, instead of at the very top. The company also made more visible the page-loading indicator, though I personally still prefer the indicator style used in prior versions.

In your column last week, you recommended add-on software to search documents for key words in Windows XP. Is there any similar software that will do the same for Macs?

It’s unnecessary on Mac because the Mac operating system comes with a fast, comprehensive search system called Spotlight that’s built right in. Windows Vista also has a very good search system built in. The reason I recommended add-on software for Windows XP is that I consider XP’s built-in search to be slow and inferior to those in these two newer operating systems.

You can find Mossberg’s Mailbox, and my other columns, online for free at the 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.