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 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.