On July 13th 2010 2 significant things happen: 1. Windows Server 2000 is no longer supported 2. Windows Server 2003 enters “extended support”
The first point means that there will not even be security updates produced for W2K any more, and it’s officially “self help” if you encounter issues.
The second point means that W2K3 will only be getting security (GDR) updates, delivered by Windows Update. Also worth noting is that there will not be a Service Pack 3 for W2K3 (which means XP x64 too, don’t forget).
Here is the Microsoft Support Lifecycle policy.
The Windows Server Division Weblog has an entry from last September where the new was announced (this is just a 6-month warning for you).
The CSS SQL Server Engineers blog has an entry which mentions this information, as well as 2 SQL Server related support announcements of a similar vein.
To avoid rushing at the last minute to get back into a supported configuration, I would recommend you take time to migrate, upgrade or retire any “important” servers still running W2K.
Upgrading to W2K3 would be a rather short-sighted approach, of course, and bear in mind that W2K8R2 is x64 only – there is no in-place upgrade method from any x86 version of Windows to x64, it’s a clean installation.
Don't say I didn’t warn you! ;)