http://www.thehotfix.net/
The Hotfix - WindowsXP SP3 Service Pack 3 Fixes, Betas, IE7, Windows Vista, Media Center
All hotfix downloads are linked directly to Microsoft. These are 100% official downloads.

Updated August 31st, 2005 - 1 New fix - 200 hotfixes total
http://www.thehotfix.net/sp3.html
WindowsXP SP3 - Service Pack 3 Fixes and Features Preview, IE7, Windows Media Center Update Emerald, Windows Vista