The very latest build of SP3 for Windows XP includes all previously released updates for the operating system, similar to previous service packs. It also includes previously released updates to the latest versions of some system components, as well as functionality for improved compatibility with Windows Vista. The application to enable the XP SP3 RC2 download can be found at the Microsoft Download Center. Running this application on a machine with Windows XP Service Pack 2 will enable Windows Update to offer XP SP3 RC2 to that machine. Build-to-build upgrades are not supported for this beta release, so if you have installed XP SP3 RC1, please uninstall it before running this application. More information regarding XP SP3 can be found on the Windows XP TechCenter.