Do you still recommend the Dell XPS One all-in-one computer that you favorably reviewed last December? I am not a techie at all but need to replace my 5-year-old Dell and was interested in an all-in-one.

Yes. In fact, I now own two of these Dell XPS Ones and use them as my Vista desktop computers, at home and in the office. I still believe, as I wrote in my review, that this Dell’s hardware is superior to that of the competing Apple iMac, though the Vista operating system is inferior to Apple’s. And the base XPS One now costs the same as the base iMac — $1,199 — instead of $300 more, as it did last year. So, if you want the Windows operating system, and like the look and convenience of an all-in-one desktop, I still favor the XPS One. You can find my review at tinyurl.com/2xw 6mv.

Will Apple’s new MacBooks and MacBook Pros run Windows directly without an intervening “virtual machine” program like Parallels or Fusion?

Yes. All Apple Macs running the current Leopard operating system, including the new laptops, come with the ability to directly run Windows XP or Vista. Using Apple’s built-in “Boot Camp” feature, you can start up the computer in Windows, instead of the Mac’s own operating system, which turns the Mac into a pure Windows machine, with no trace of the Mac operating system running. The upsides of this approach are maximum Windows speed, and compatibility with the most graphics-intensive Windows programs, including games. Note that, to run Windows on a Mac, you must obtain and install a fresh, boxed, full version of XP or Vista. Apple doesn’t supply Windows.

I have a Yahoo email account, and wonder if Yahoo allows receipt and storage of email directly via a computer email program, such as Outlook, or is it all Web storage? Can you do both?

Yes. Yahoo offers a “Plus” option, for $20 a year, that permits users to receive and store their Yahoo email using a locally installed, instead of Web-based, email program. This approach does work with Microsoft Office, as well as many other local email programs. And you can still use Yahoo’s Web-based email interface at the same time. The Plus option also includes other benefits, including the elimination of ads and a doubling of the size limit on individual messages, to 20 megabytes.

• 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 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

If I buy a PC with an AMD processor instead of an Intel one, will I run into any compatibility issues with common software like Vista or Office 2007?

No, as long as the AMD processor, and/or its accompanying graphics and other chips, called a “chip set,” are rated as being able to handle the graphics in the version of Vista you are buying. Each chip company makes some low-end models that handle certain tasks more slowly than their mainstream or top-of-line models. And gamers are often particular about which chip sets they buy. But, in my experience, roughly comparable AMD and Intel processors and chip sets are equally compatible with common software like Office and Windows.

I have been using the Netscape Web browser for years. I am interested in shifting to using the Firefox browser. How do I transfer my extensive list of book marks from Netscape to Firefox?

Firefox will import your Netscape bookmarks automatically during the installation process, just as it can automatically import bookmarks from other browsers like Internet Explorer, Safari and Opera.

Friends who use Macs tell me they have a removable backup device that backs up their entire hard drive, including programs. Is there something similar for PCs?

You appear to be referring to Time Capsule, which is an Apple hardware product that combines a hard disk and a wireless base station and is meant to work with the Mac’s built-in Time Machine automated backup feature. The answer is that there are many backup drives for Windows PCs, and that lots of them work with Macs as well. All the major hard-disk makers sell external hard disks that connect to a PC either directly, or over a network, and which come with relatively simple backup programs. Some of these programs will do complete, automated backups of everything on your PC, including applications. Even Apple’s Time Capsule can be used to back up files from Windows PCs, though it doesn’t come with Windows backup software, and setting it up for Windows is slightly trickier than doing so on a Mac.

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

I want to buy a new ultralight laptop for travel. Few are available with Windows XP, which I would prefer. If I get a Vista machine, will I have compatibility issues with transferring files back and forth between it and my older laptops, both of which have XP operating systems and MS Office 2003?

Your Microsoft (MSFT) Office files, and other standard files, such as photos, songs and PDF documents, should all be compatible with both Vista and XP. While Vista has compatibility problems with some programs and some hardware, in my tests I have never found that Vista caused compatibility problems with standard, common types of files.

I plan to install Windows XP on my Apple (AAPL) iMac using Boot Camp. Whenever I am using the Windows side of the machine, I plan to shut off access to the Internet — no Web browsing or email. I even intend to unplug my wireless base station. Will this protect me from getting the Windows viruses?

Well, that’s a drastic plan, but it will probably work, since most viruses and other malicious software are acquired via email or Web sites. However, by cutting yourself off from the Internet, you may make your computer less useful while running Windows. Many programs have Internet components, and those that run locally often download new versions and features over the Internet. Plus, Microsoft distributes updates for Windows and Office using the Internet, including security fixes. For those reasons, it might be more effective to install security software on the Windows portion of your Mac and leave the Internet connection on.

I have a relatively new PC with Windows Vista. Typically, I may have five or six programs running at the same time, sometimes with multiple documents open in each one, and I like to leave my PC this way. However, I’ve noticed that every few weeks or so, Vista has an annoying tendency to restart my PC when I’m away from it, and I see a message that “Your computer was restarted to finish installing updates.” Is there any way to prevent or minimize this?

Yes. In the settings for Microsoft’s automatic update service, called Windows Update, the recommended option is to automatically download updates and install them. The second step, installing the updates, can lead to a restart. But you can change the settings to minimize or eliminate the annoyance this causes.

You can choose a specific schedule for installing the updates at a time when you won’t be interrupted. Or, you can choose an option called “Download updates but let me choose whether to install them.” A third option is called “Check for updates but let me choose whether to download and install them.” You could opt out of the update program, but that could leave your PC vulnerable to malicious software.

These options can be found by opening the Windows Security Center, then clicking on “Windows Update” at the upper left. Then, in the next window, click on “Change settings” in the left column. Similar settings are also available in Windows XP, by opening the Security Center and clicking on “Manage Security Settings for: Automatic Updates.”

• 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.

We are connected to Comcast (CMCSA) cable and use no antennas. Will we need one of the government-subsidized converter boxes next February?

Not if you are using a cable set-top box, like the vast majority of cable customers. If you are one of the minority of cable households whose TVs use an internal cable tuner, you may need a converter box. To be sure, contact your cable company or TV manufacturer.

In your laptop buying guide last week, you recommended buying a machine equipped for the “n” type Wi-Fi of wireless router. I was under the impression that this has not yet been standardized. Is that wrong?

The engineering committee that has been debating the standard for years has not yet completed its work, but the market has simply moved ahead on its own. This new, faster version of Wi-Fi is being built into routers, computers and other devices by nearly every major manufacturer. In my limited tests, I have found no compatibility problems, and it is backwards compatible with the older “g” and “b” standards.

Is the Mac immune to viruses? If not, do you have a recommendation of the type of antivirus software one should procure and load onto a Mac?

No personal computer or personal computer operating system of which I am aware is “immune” to viruses, spyware or other malicious software. That includes Apple’s (AAPL) Macintosh and its operating system, Mac OS X Leopard. Hackers have demonstrated the ability to invade the Mac. However, there are only a handful of viruses or other malicious programs for the Macintosh that have successfully spread beyond the lab. And these have harmed only a small number of actual users.

Of the well over 100,000 known viruses, spyware programs and other malicious software applications that are about in public, all but this handful are written to run on Microsoft (MSFT) Windows, and cannot operate on the Macintosh OS. For that reason, I don’t believe Macintosh owners need security software, unless they install and run Windows on their computers. If they do run Windows, Mac owners are well advised to purchase and install Windows security software to protect the Windows portion of the machine.

Having said that, I do not mean that Mac owners should be blind to security threats that don’t involve viruses or spyware. Just like Windows users, Mac users can succumb to what is called “social engineering” — scams and schemes that operate via email and Web sites that are often authored by crooks but made to look official. So, like Windows users, they must be on their guard.

You can find Mossberg’s Mailbox, and my other columns, online free at the 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 direct audio input jacks for portable MP3 players in automobiles, Internet browser compatibility with Windows, and editing a computer’s Registry.

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.

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.

Do any car makers offer audio input jacks for portable MP3 players so you can play their output through automobile sound systems? I think this would be better than relying on headphones while driving, or using an FM transmitter.

You’re correct that a direct audio input jack makes for much better sound than an FM transmitter, and is safer than driving with headphones. But, for years, car makers have generally neglected to include these simple, inexpensive jacks. A few models, here and there, have had them, especially if you order optional sound systems. For the most part, however, if you wanted an audio jack, you had to pay someone to install one, or buy an after-market radio that included one.

Lately, however, as MP3 players have become more popular, the industry has begun to respond. For instance, General Motors has announced it plans a standard built-in audio input jack on a new 2006 Chevrolet model called the HHR, and on other models from Chevy, Saturn, Buick and Cadillac.

However, these and other audio input jacks aren’t as capable or elaborate as the special connections for Apple’s iPod music players being offered by BMW, Mercedes-Benz and other car makers. These systems, which require dealer installation, allow you to actually control the song selection and playback from the car’s normal audio controls. Audio input jacks like those GM is planning allow only volume to be adjusted from the car’s audio controls.

I installed Internet Explorer 6.0 SP1 for my Windows 98 computer. I am wondering if the two are compatible, because I keep getting booted offline. Any ideas on why this is happening? Is Firefox compatible with Windows 98?

The Service Pack 1, or SP1, version of the Internet Explorer 6.0 Web browser, is indeed compatible with Windows 98. So is the competing Firefox browser. Without examining your PC and Internet setup, I can’t say why you’re getting bumped offline. But it’s unlikely it has anything to do with your Web browser.

The cause is much likelier to lie somewhere in the combination of your network-connection configuration, your Internet hardware and your Internet provider. Even though you can access the Windows Internet connection control panel through the Tools menu in Internet Explorer, Web browsers don’t really control a computer’s connection to the Internet. They merely allow users to navigate the Web once a connection is established.

My computer is becoming sluggish, and a friend recommended I edit or clean up something called the “registry.” What is it, and how do I edit it?

If you have to ask, I strongly advise you against trying to edit it. The Registry is a central database in Windows that contains configuration information for the operating system, all your programs and your hardware. It can override other settings on your computer, and it wasn’t designed to be easily accessed or changed by users.

It is possible to edit the Registry, or to run utility programs that “clean” the Registry by supposedly deleting settings for programs you have uninstalled. But it takes technical skill to do so. If you inadvertently mess up the Registry, you could cripple your computer. So, I believe that only technically skilled users should even think about tinkering with the Registry. If you believe you should make changes to it, and you aren’t a techie, hire an expert to do so.

* * *

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