Maybe this is old news or a repost, but I just saw this morning that SP2 is released for both Server 2003 and XP64. I'm downloading this now to try on a test server. It's also available in Windows Updates. Have at it, and let us know if it breaks anything.
http://www.microsoft.com/technet/windowsserver/sp2.mspx
http://www.microsoft.com/technet/windowsserver/sp2.mspx