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.

In last week’s Mailbox, you said that Windows XP machines can slow down over time unless you do “a lot of techie maintenance.” What did you mean? I regularly defragment the hard disk, tweak the registry, and clean out temporary files, but my PC is still slow.

All of these things are helpful, though I don’t recommend that nontechie users “tweak” the Windows registry, which contains vital program information that can mistakenly be removed or altered if you don’t know what you’re doing. Another speed-enhancing tactic is to use a program like Startup Cop Pro (snipurl.com/b4v91) to prevent unneeded programs from running at startup, and one like PC Decrapifier (pcdecrapifier.com) to clean out craplets — unwanted pre-installed programs.

However, what I had in mind when I wrote that was something more drastic, something a number of techies I know do annually: a complete replacement of Windows. This involves first backing up all your files, and then performing what’s called a “clean install” of Windows XP that wipes out everything on the PC and starts fresh. You then would copy back all your data files and re-install your programs.

This can make the computer feel like new, but the problem is that it can be tricky and tedious for nontechie users. Depending on the source of the copy of Windows XP you are using for the clean install, you may have to locate and re-install drivers for peripheral hardware and for hardware features of your particular make and model of PC. You may run into licensing and activation issues with your re-installed programs. And you may have to download numerous patches and upgrades for Windows itself and for your programs.

I am considering buying one of the new MacBook Pro 15″ laptops. What do you think of the keyboard on this laptop? Is it easy to type on compared to other laptop keyboards? What do you think of the shiny screen?

Because keyboard and screen preferences vary from person to person, I strongly urge all laptop shoppers to try out models they are considering before buying, even if only for a few minutes at a retail store. Having said that, I find the MacBook Pro keyboard to be very comfortable and easy to use, with good key spacing and feel. I personally prefer matte screens to glossy ones, but own laptops with both types and find the glossy ones acceptable, if not optimal.

I use the Windows Mail program that came with Vista on my computer. You say Windows 7 won’t come with that program. Is there something similar that can be installed?

Microsoft will encourage people to download a similar free program called Windows Live Mail, which is closely tied to its Live online service. Or, you could switch to a competing email program, or rely on Web-based email.

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 new H-P (HPQ) laptop and there are several preinstalled media-playing interfaces that have been foisted on me. Do I really need all of these interfaces? Can’t I just get all of this media to run through Windows Media Player or iTunes?

Since you weren’t specific, I don’t know what media software came with your new laptop. I’m sure some of it may have been redundant “craplets” — the unwanted software PC makers load onto their machines in order to collect a fee from the programs’ publishers. And you are correct that many of the most common audio and video file types can be handled by Windows (MSFT) Media Player and iTunes.

However, the Internet is full of media file types that are best played, or can only be played, in specialized software — either separate applications on your computer or online players that are enabled via your Web browser. So, over time, most users will collect additional players, or plug-ins for their Web browsers, that will supplement their main media-playing program. One way to see if the media software on your new computer is necessary is to test what types of files it handles. If you can open and play these same files in Windows Media Player or iTunes, and you prefer to do so, then you probably don’t need the added software.

If I am running Windows Vista on my iMac desktop using Parallels, will Apple’s Time Machine backup program automatically preserve the Windows hard disk, too?

Yes. Parallels, and its competitor, VMWare Fusion, create virtual Windows hard disks inside a Macintosh. When you are running Parallels or Fusion, Windows sees these virtual hard drives as if they are distinct physical disks. However, they are in fact just very large files on your Mac’s hard disk. So Apple’s (AAPL) Time Machine backup program treats them like any other file and backs them up. Time Machine can also restore these virtual Windows hard disks, in their entirety, just as it can restore other kinds of files.

There are some caveats, however. Time Machine treats each virtual Windows hard disk as a big, unified blob of data, so it cannot peer inside them to recover individual Windows files you may have accidentally deleted while running Windows programs. Also, if your virtual Windows hard disk is large, and it changes often, then using Time Machine to back it up may suck up a lot of space on your backup drive, as numerous archived versions of the file accumulate.

I currently have a DVD player and a large stack of DVDs that I play through my analog TV set. After the 2009 digital TV conversion, will I still be able to use my existing DVD player and play my existing DVDs, even if I buy one of the government-subsidized converter boxes?

The FCC says DVD players and other add-on gear “will continue to work, even if they are only analog-capable.” But it adds that “manufacturers are producing a number of different connectors to hook equipment together and improve picture and sound quality. Check with your equipment retailer to determine the types of connectors that will work with your equipment.”

In other words, while there’s no inherent conflict, it all depends on your particular DVD player, your particular TV set, and how you have them connected. The best thing to do is consult closely with the dealer or manufacturer selling the converter box so that you understand how it can coexist with your current DVD player setup, or how you might have to alter your current setup.

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 looking for information about how I can export my Favorites and Address Book from my AOL account to another browser and any other email service.

There may be multiple methods for doing this, but one simple approach is to use a service called TrueSwitch, which is specifically designed for this purpose. It can be found at www.trueswitch.com.

Is there an application that will uninstall all the “craplets” and their preferences from a Windows machine?

Yes. It’s called “PC Decrapifier,” and can be downloaded at pcdecrapifier.com. It is designed to remove from a new Windows PC all of the unneeded trial programs, add-on programs and advertising come-ons that PC makers typically cram onto the computer that are collectively known as “craplets.” These items can slow down a new machine and occupy disk space better used for programs and files you actually want.

I’ve recently purchased a laptop with Vista Home Premium as the operating system. Is there a way to remove the Vista operating system and use Windows XP?

Yes, such an operating system “downgrade” is possible, but it isn’t for the faint-hearted or the average, nontechnical user. There are many obstacles, but let me list just the major ones. For one thing, the process involves wiping out everything on your hard disk. That means you will need to carefully copy all of your personal data files to a backup disk so you can restore them after the downgrade. In fact, you should clone your entire hard disk if possible so you can revert to Vista if the downgrade fails. You will also need a legal copy of Windows XP, or — better yet — a legal Windows XP recovery disk from your PC’s maker that is customized for your machine’s hardware and factory-installed software.

If you can’t find an XP recovery disk tailored for your particular PC, you will need to assemble a collection of “drivers” — the software programs that make your computer’s hardware features work — that are compatible with Windows XP. This can be difficult, or even impossible, as a Vista machine may contain new hardware components for which XP drivers are hard to find or may not even exist.

If you aren’t a techie, and you desperately want to downgrade to XP, I strongly suggest hiring an expert to take on the task. But the best solution for XP fans is to buy a machine with XP preinstalled in the first place.

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.

My IT department will not turn on the feature in our servers that would allow me to receive corporate email on my iPhone. This has forced me to revert back to my BlackBerry Pearl. Can I transfer my iTunes music to my Pearl?

It depends on what you mean by “iTunes music.” If you mean music you bought from the iTunes store in protected format — which describes most of the store’s catalog — the Pearl can’t play it, unless you go through a laborious multistep process to convert it to unprotected files. If you mean unprotected music that is managed by the iTunes program on your PC, the Pearl can handle it as long as it is in open formats supported by the Pearl, including the MP3 or open AAC formats.

To get these files into your Pearl, simply use the music-transfer software that came with the Pearl to copy the songs from your computer’s hard disk to either the Pearl’s internal memory or to a flash memory card you may have in your Pearl.

I recently purchased a new iMac with the Leopard operating system, and have installed Windows Vista on it as well, using Leopard’s Boot Camp feature, so the Mac can boot into either OS. I would like both of those operating systems to share an external hard drive so I can back up my files. Is it possible to do that?

Yes, provided you follow one of two scenarios. The first would be to format the external drive as a Windows drive, but be careful to use the Windows format called “FAT32,” not the one called NTFS. Out of the box, Macs can see all Windows drives and can read from them all. But they can only save files to Windows drives that use the FAT32 system for organizing files. The downside of this is that the FAT32 system only allows files of up to 4 gigabytes each.

The other scenario would be to use a Mac-formatted external drive, which doesn’t have that limitation. Of course the Mac operating system can handle such drives perfectly, but Windows can’t even see them. However, in your Vista setup, you can install a third-party Windows program called MacDrive 7, which allows Windows to both read from, and write to, Mac-formatted drives. I have tested it successfully with Vista under Boot Camp on an iMac. The $50 program can be downloaded from mediafour.com.

The hard disk on my new Sony VAIO laptop is filling up fast. It is trying to get me to watch a lot of movie trailers. Is all that video stored in my machine somewhere and if so can I dump some of it out?

If your Sony laptop is like mine, not only are the unwanted movie trailers pre-loaded on your hard disk, but so are the entire movies, which Sony actually charges you to watch. In my case, these files took up over 4 gigabytes of precious disk space. This is a particularly outrageous example of what I call “craplets,” unwanted trial software that litters new Windows desktops. You can delete these files and reclaim all that disk space without any harm to your computer.

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. This week my mailbox contained questions about Windows Vista complaints, using antivirus software when running Windows on a Mac, and transferring large files.

In various past columns, you have complained that Windows Vista boots slowly and that it is incompatible with some software and hardware. Is this situation improving?

Microsoft claims that neither complaint affects most users, and that the minority of cases where they do is being whittled down steadily. I expect that the incompatibility issues, at least, will diminish over time. But I am still receiving reader complaints about incompatibility, so I have to assume that this issue remains real, at least for some people. The slow start-up issue will be harder to cure, as it involves factors like add-on trial software, called craplets, that are beyond Microsoft’s control. Officials at a number of Windows PC makers tell me they are beginning to get the message that people hate craplets. But I am still observing slow boot times in new Vista PCs I test and still see plenty of craplets.

If I run Windows on a Mac, do I need two copies of antivirus software, one to run in the Windows environment, and one to run in the Mac operating system?

You need only one copy, to run in the Windows environment. Macs have essentially no virus problem, and thus don’t need antivirus software. However, some Mac users install it to be extra safe, or to kill viruses that they fear might be passed on via email or over networks to people using Windows.

In last week’s Mailbox, you advised someone that he could copy a 25-gigabyte file from a Mac to a Windows PC using an external hard disk formatted for the Windows FAT file system. But I believe that won’t work. Do you have another solution?

You are correct that I erred. I forgot that the FAT file system, the only Windows format to which Macs can save files, is limited to file sizes of up to 4 gigabytes. This is almost never a problem, except in the case of extraordinarily large files. I did offer several alternate solutions last week, including using a network or cable transfer. But here’s another: You can use a Mac-formatted external hard disk, or a Mac-formatted iPod acting as a hard disk, to transfer the file, provided you have installed on the Windows PC special software that allows Windows to read Mac-formatted disks. This software is called MacDrive, costs $50, and can be purchased at mediafour.com.

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.

Write to Walter S. Mossberg at mossberg@wsj.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 whether to buy a smart phone now or wait for the iPhone, boosting the range of a wireless connection, and removing junk programs that come with a new computer.

I am in the market for a new smart phone. Should I wait for the Apple iPhone? When will it be available and when will you review it?

Apple says the iPhone is on track to go on sale in “late June,” and I expect to be able to test it and publish a review around that time. There will also be many other reviews around then that you can consult.

I stand by my earlier advice, which is that people shopping for a smart phone, who can wait until then, and who could imagine shelling out $499–the iPhone’s base price–should wait to read the reviews of Apple’s first phone and take a look at it before making a decision. However, if you need a smart phone now, or can’t imagine spending that much, then you can ignore the hype and buy a BlackBerry, or a Treo, or another competitor.

Three other key factors could also make you reasonably ignore the iPhone. It will lack a physical keyboard, relying on virtual keys that appear on the screen, so if you prefer a real keyboard, the iPhone would be a nonstarter for you. Also, it will only work on the AT&T wireless network (formerly Cingular) in the U.S. So, if you prefer another wireless carrier, forget the iPhone. Finally, it will only operate on a relatively slow network technology, called EDGE, so if you want a smart phone that operates on the fastest cellular networks, the iPhone is the wrong choice, even though it will also include Wi-Fi wireless networking.

The wireless connection to my wife’s Windows XP computer keeps going down. The computer is about 75 feet (but through three walls) from my Dell Truemobile 2300 router. Should I assume I need a better, more powerful router? And, finally, will it also connect to my MacBook Pro laptop?

A more powerful router might help, but wireless reception varies greatly depending on home construction and layout. You might look for a new router that features a technology called MIMO, which I have found in my tests can improve both speed and range. Even with a new router, you might also have to move its location. There are also various boosters and repeaters that can be used, though some of these require more technical expertise to install than most folks have.

One good method for extending the range of a wireless connection is to buy a set of so-called powerline adapters. These carry your network signal over plain old electrical lines, and some models allow you to create a wireless network by plugging a wireless router into such an adapter in a distant room. I described these adapters in more detail in a column you can find at: ptech.allthingsd.com/20060817/powerline-adapters-access.

In my own home, I have used both MIMO routers, and powerline adapters, successfully with mixtures of Windows and Apple Macintosh computers, including the MacBook Pro, and various Dell, Lenovo and Hewlett-Packard laptops.

Can I remove the junk programs that came with my new computer–the ones you call “craplets”–by using the “Add or Remove Programs” control panel in Windows?

Yes, but that is a tedious manual process and may not get them all. Also, in Windows Vista, that control panel has been renamed and is now called “Programs and Features.”

Instead, I would suggest first downloading and running a free program specifically designed to eliminate craplets, the crippled trial programs and advertising come-ons that are now packed into so many new Windows PCs. This program is called “The PC Decrapifier” and can be found at pcdecrapifier.com. If this program misses a few of the junk items you want gone, you can then use the manual method.

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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