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 read your recent column about running Windows on a Mac. Is there a way to run the Mac OS X operating system on a PC, like a Dell or a Sony?

Yes, but it is really only for tinkerers and hackers, and even then, it may not work fully or smoothly. Apple makes the process difficult, both technically and legally, because, unlike Microsoft, it is not in the business of selling its operating system for use on other companies’ hardware.

Therefore, I know of no simple software for average consumers that can install OS X on a non-Apple computer without any technical knowledge and with full assurance that the operating system will be completely compatible with the hardware. There is nothing on the market like the products that allow people to run Windows on a Mac.

A small number of techies do install Mac OS X on non-Apple PCs every day, and some people have created software to make this possible for people with plenty of technical knowledge. There is even a company called Efix that is selling a hardware module that it says will make this easier. Its maker warns the product is only for “enthusiasts” and it requires that you attach it to the computer’s internal circuitry. Also, it only works with certain types of personal-computer hardware.

One more thing: Apple takes the position that its licensing terms limit the use of OS X to Apple hardware, so, even if you can pull it off technically, there could be legal jeopardy involved. In fact, Apple is suing a company called Psystar that sells non-Apple PCs with OS X pre-installed.

I have a new PC that came with a 64-bit version of the Windows operating system. It gives me a choice between using a 32-bit Internet Explorer or a 64-bit Internet Explorer. Which should I use?

The 64-bit version of Windows, which is rarely used by average consumers, can make the computer faster, but only when running programs that have been written in special 64-bit versions. In the consumer arena, there are too few such programs, and thus too little benefit, to justify paying extra for 64-bit machines. In fact, most people who have computers running 64-bit Windows are mostly using older 32-bit programs, which run fine, but aren’t made quicker.

So, the 64-bit version of Internet Explorer may run faster. But there is a downside. Because of the relative rarity of 64-bit users, some browser add-ons and toolbars and some of the Web technologies that power the features of Web pages, aren’t compatible with the 64-bit version of IE. On top of that, you may not notice any huge speed difference as the perceived speed of Web browsers depends more on the speed of your Internet connection than anything else. So, for now, I would stick with the 32-bit version, for compatibility’s sake. You can always install the 64-bit version later, if you decide that the Web sites you frequent and the add-ons you use work well with it.

I am running a Mac with Windows XP Pro in Boot Camp, which requires rebooting to change operating systems. Is there some way I can use my already-installed Boot Camp setup as a virtual machine using VMWare Fusion, so I can run my Windows and Mac programs side by side?

Yes, there are two ways. First, Fusion allows you to treat the Boot Camp section of your hard disk, called a “partition” — which is essentially a separate Windows PC stored on your Mac — as if it were a “virtual machine.” This approach still allows you to reboot the entire Mac into Windows when you’d like to do so, in order to perform the few tasks that Fusion can’t handle, such as advanced 3D graphics.

The second approach is to simply import the Boot Camp installation and turn it into a purely virtual Windows computer, as with any virtual Windows machine you would create in Fusion. If that meets your needs, you can then actually remove your original Boot Camp Windows installation, which will likely free up some hard disk space. To do this, just select your Boot Camp partition, which Fusion automatically detects, and click on Import under the File menu.

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

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

After reading your positive review, I downloaded Firefox 3.0, only to discover that some of my favorite add-ons, including a search toolbar, are incompatible. What can I do about this?

Wait. As I noted in the review, when major new versions of Firefox come out, it takes a while for some of the many add-ons for the browser to be updated so they are compatible with the new version. Because these are written by a very large number of different companies and individuals, the process will be gradual, and some will be updated more quickly than others.

As for search toolbars, like those from Google (GOOG) and Yahoo (YHOO), I doubt that most people still need them. When they first came out, these toolbars provided things the top browsers lacked: a permanent search box, pop-up blocking and a few other useful features. But all the major browsers now provide these things without requiring the installation of any external toolbar. The companies that make the toolbars can use them to sell advertising or attract you to their search engines. But, for many users today, they are redundant.

I don’t want to run antivirus software constantly, but I would like to periodically run a program that could scan my computer and remove viruses and the like. Does such a program exist?

Yes. Here’s one example. Microsoft (MSFT) makes a small, free program called the Malicious Software Removal Tool that looks for, and tries to remove, a limited number of the worst examples of malicious software. It can be downloaded at www.microsoft.com/security/malwareremove.

However, this isn’t a comprehensive antivirus program. Microsoft says it detects and removes only “specific, prevalent malicious software,” and advises that “You should also use up-to-date antivirus software to help protect your computer from other malicious software.”

I am in the market for a laptop. I was considering a Dell (DELL) or an H-P (HPQ) but have learned that Apples now run Windows. I have financial (Quicken) and other business files (Excel, Word and PowerPoint) that would need to be transferred to the new computer. Would this be possible on an Apple (AAPL)?

Yes, in the same ways you could transfer files from one Windows PC to another. For example, you could burn them to a CD or DVD, copy them to an external USB drive, or transfer them over a network or via the Internet. In fact, if you buy your Mac at an Apple retail store, the store’s staff will move your files over free, or for a modest fee, depending on which folders, and how many, you want transferred.

Once the files are on the Mac, you can either use native Mac programs to read and/or modify them, or you can install Windows and run your usual Windows programs to handle the files.

For instance, even if you never installed Windows on an Apple, your Excel, Word and PowerPoint files could be used in the Mac version of Microsoft Office. However, the Mac version of Quicken isn’t as compatible with the Windows version’s files. So, for Quicken, I suggest installing Windows on the Mac and running the Windows version of Quicken.

• 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.