Windows Server 2003 SP2 Released
Go get Windows Server 2003 SP2 and start doing your test deployments!
The best search is to look for "Service Pack" and sort by date at the MS Downloads site.
The downloads include a blocking tool for preventing an AU installation.
I'm looking for x64 XP info now...
[edit 3:13 pm ET - the x64 XP update is available as well as part of the 2003 x64 update, thanks to Susan Bradley for finding this and telling me about it via the ActiveDir list]