While Microsoft was supposed to release Windows XP Service Pack 3 (SP3) on April 29, 2008, the service pack only became unofficially available on the download.windowsupdate.com domain. Today, XP SP3 has officially hit the Release to Web (RTW) milestone. In other words, SP3 is available both on Windows Update and the Microsoft Download Center (network installation, ISO CD Image, and Checked build).

The final build of SP3 (5512) reportedly includes 1,073 fixes, including every security update, out-of-band release, and hotfix released since Windows XP SP2 hit Microsoft's servers back in August 2004. The release notes for SP3 have also been updated, as has the MUI pack. Also, make sure you know what to do with your version of Internet Explorer before installing the service pack.

The delay of SP3 was due to a problem XP SP3 and Vista SP1 has with the Microsoft Dynamics Retail Management System (RMS). There is now a filter to block Windows Update from offering Windows XP SP3 or Windows Vista SP1 to systems with RMS. Although Microsoft has still to confirm the date, SP3 should be rolled out via Automatic Updates on June 10, 2008. TechNet and MSDN subscribers already have access to SP3. In addition to the XP SP3 release, automatic distribution of Windows Vista SP1 has also resumed. Microsoft is still working on a fix for the RMS problem.