Just wondering. Does the normal XP Service Pack 2 work for XP Media Center 2005? Or does Media Center 2005 already contain Service Pack 2? Does Media Center 2005 use normal XP post-SP2 updates?

MCE 2005 has SP2 already integrated. All XP updates are also fully compatible with MCE. You will also need to install Update Rollup 2, and then October 2006 Rollup Patch for Media Center 2005 Rollup 2 (KB925766). That should bring you up to date.

Be sure to install Update Rollup 2 ASAP after MCE is installed. There are a number of updates (included in UR2) that if installed seperately will cause the instalation of UR2 to fail. http://blogs.msdn.com/astebner/articles/487537.aspx