Windows XP Service Pack 2 is finally being released after 2 years in the making, a few new features and lots of bugs fixes. This will probally be the big update for awhile so I highly recommend every get it. Its been released to MSDN subscribers currently and should be released to the gerenal public next monday. If your going to grab it off the torrent sites like I did *cough*, here are some this to look for (other than the MS digital signature):
File: WindowsXP-KB835935-SP2-ENU.exe
Size: 278,927,592 bytes
MD5: 59a98f181fe383907e520a391d75b5a7
CRC: 0x046F12B1
UPDATE:
The Offical MS link is now up, which turns out to be the same that leaked to the web on last friday, which I installed: