Washington - Microsoft may be devoting most of its resources to Windows Vista, but that doesn't mean it has forgotten the world's most popular operating system: Windows XP. In fact, the company has just unveiled the latest version of XP, Service Pack 3 (SP3), and is making the update available free to all registered XP users.

As with any service pack, though, it's a good idea to know what you're getting into before you give Microsoft the go-ahead to install XP3 on your machine. Read on to find out.

Q: What's new about XP XP3?

A: Most of what's new about SP3 is under the covers. The significant improvements include security enhancements that make using the operating system safer when online.

There are also some features that make XP compatible with some features of the new Windows Server 2008, as well as the ability to install the operating system without an installation key if you have SP3 on an installation disk. As with Windows Vista, you'll have 30 days in which to register the operating system if you choose to go this route.

You will also see the inclusion of Windows Media Player 11 and Internet Explorer 7 in SP3, but those components have been available as separate downloads for some time to registered users of XP.

The release notes for SP3 state that if you already have Internet Explorer 7 on your system prior to installing XP3, you will not be able to uninstall Internet Explorer 7 after applying the service pack.

Q: Are there any performance improvements in SP3?

A: Microsoft says that SP3 should perform no better and no worse than SP2, but there are anecdotal reports from early adopters that suggest that you might see some small performance gains after installing SP3. No one has yet reported a slowdown as a result of installing SP3.

Q: What are my options for installing SP3?

A: Microsoft encourages registered users of XP to upgrade to SP3 by using Windows Update (http://www.update.microsoft.com), but you can also download the full upgrade package, which comes in at over 300 megabytes.

Do a Google search for "Windows XP Service Pack 3 Network Installation Package" to find the site that offers the full package. Having the full SP3 file available offline is handy if you're upgrading computers that may not be connected to the Internet.

Q: I have the original Windows XP on my computer. Can I install XP3 directly or do I need to install the other service packs first?

A: You need to have at least Windows XP SP1 on your machine before you can install SP3. Microsoft recommends that you install SP2, but that's not required. If you use Windows Update to upgrade your current version of Windows XP, to at least SP2, then you'll be fine.

Q: Will SP3 break any of my applications?

A: Microsoft delayed the release of SP3 at least once due to issues concerning compatibility with existing applications, especially security and malware programs, but most of those problems have been addressed. A compatibility issues with Windows Home Server may still exist, however.

Some users of SP3 have reported that SP3 destroys their ability to connect with a Windows Home Server machine. Most of the Windows Home Server computers are set up to back up client machines automatically. Editing the registry can apparently help, but this is not for the faint of heart. There have been additional compatibility issues reported with programs that transform the Windows XP shell or interface.

Those who use primarily mainstream applications should experience no compatibility glitches with SP3, however.

Q: Will Microsoft release more service packs for XP?

A: SP3 may very well be the last service pack that XP sees. Microsoft has already announced that it will no longer support Windows XP beyond 2009, and given that over three years have elapsed since the release of SP2, Microsoft probably would not have the time - or desire - to release another service pack for XP. Microsoft's efforts are now focused on migrating the world to Windows Vista.

--- Have a computer question? Send it to the Computer Helper at jayd@csi.com. (dpa)