Microsoft has announced that it plans to release Windows XP Service Pack 3 (SP3) to manufacturing on March 24, 2008. A feature set overview has been posted by Microsoft and details new features available separately as standalone updates to Windows XP, as well as features backported from Windows Vista, such as black hole router detection, Network Access Protection and Windows Imaging Component.
According to a file released with the early beta version and relayed onto the Internet there are a total of 1,073 fixes in SP3.
This update to Windows allows it to be installed without a product key, and be run until the end of the 30-day activation period without a product key.
On December 4, 2007, Microsoft released build 3264 of a release candidate of SP3 to both TechNet and MSDN Subscribers. On December 18, 2007, this version was made publicly available via Microsoft Download Center. The latest public release of SP3 is Release Candidate 2, which was released to the private beta-testing group through its connect website on February 6, 2008, with a build number of 3300. On February 19, 2008 build number 3311 of SP3 Release Candidate 2 was released for public beta testing. In order to be able to download and install SP3 Release Candidate 2 via Windows Update or Microsoft Update, a script must be installed and any earlier version of SP3 must first be removed. SP3 Release Candidate 2 can also be downloaded by way of the Microsoft Download Center. The latest release of SP3, build 5503, is a private release that was leaked on March 12, 2008. Although an official release, Microsoft has warned against installing this version, stating, "This build was not intended for public release and anyone who has that build and is not part of the private beta is working with bits that Microsoft can't verify the integrity-it's possible the bits may have been modified with malware or other bad code that Microsoft hasn't tested.
Microsoft noted SP3 will update both Internet Explorer 6 and version 7 independently, and not require migrating to the next version.
Source ::: http:://www.wikipedia.org