As Paul Thurrott reported in his WinInfo Daily UPDATE article "Microsoft Ships Windows XP SP2 RC1 to Testers," http://www.winnetmag.com, InstantDoc ID 42076, Microsoft has released the first release candidate (RC) build of Windows XP Service Pack 2 (SP2). Despite Microsoft's previous statements to the effect that service packs would no longer contain feature upgrades, XP SP2 RC1 contains many elements that qualify as features, ranging from a new client security and privacy configuration tool to a seriously upgraded personal firewall.
You can find a detailed description of the changes that SP2 RC1 will make to your XP installation in the Microsoft article, "Changes to Functionality in Service Pack 2 for Microsoft Windows XP," at http://www.microsoft.com/technet/prodtechnol/winxppro/maintain/winxpsp2.mspx . The article states that it doesn't describe all the changes that the final release of SP2 will include. If you plan to evaluate SP2 RC1, keep in mind that the final release of SP2 will include some changes that aren't in RC1.
Check out the XP SP2 Technical Preview Program home page at http://www.microsoft.com/technet/prodtechnol/winxppro/sp2preview.mspx . There, you'll find the download link for RC1 (which is a whopping 273MB; plan your download accordingly) and links to all the Microsoft resources dedicated to XP SP2.
You might want a heads up on what to expect from XP SP2 RC1 before you take the plunge and try it out. To get a feel for RC1, I installed the software on three different XP-equipped computers. I installed RC1 on a fresh installation of XP that I first updated to SP1; on an updated XP setup with various applications installed, including common office-automation software and 10 other common applications and system utilities; and on a heavily used computer with dozens of installed applications and a series of OS upgrades.
As you might expect, the fresh installation of XP SP1 had no problems with the SP2 RC1 upgrade. I had no errors, and applications I installed after the upgrade worked properly. Unfortunately, the next two installations left me less sanguine.
The second installation started just fine but then had problems when some applications failed because they couldn't access the network. SP2 RC1's new personal firewall was blocking the applications, but by the time Windows prompted me to allow the applications network access, they'd already failed. I solved the problem by configuring the personal firewall to let applications that needed to access the network do so. After I rebooted the system, the applications that had previously failed loaded and ran properly. However, I discovered a tougher problem: My network-monitoring tools failed to run. The tools returned load errors and were clearly not compatible with SP2 RC1. I sent a few notes to the ISVs who provided my tools, and they're working to solve the problems.
The third system was a complete disaster. The installation proceeded without error, but the computer failed to reboot and returned various driver error messages. Recovery proved impossible because Automated System Recovery (ASR) failed, as did my attempt to upgrade or reinstall XP. (The installation routine returned a fatal error after about 20 minutes, stating that the ID of the installed OS was invalid.) I had to restore the computer from a disk image backup to return to its previously functional configuration.
As you can see, running SP2 RC1 is something of a gamble. Take Microsoft's advice to heart: Don't install SP2 RC1 on production systems and make sure you back up any systems on which you intend to run RC1 before you install it.