As already earlier posted, the extended support for windows 2000 server will end on 13th July 2010. After this date, no more security updates, fixes, patches and/or service packs will be delivered anymore. There is only online and self help support still available via the common TechNet/MSDN and Knowledge base articles.
Further information and general support lifetime info will be found here as well: http://blogs.technet.com/steve_chen/archive/2010/01/27/end-of-support-lifecycle-for-windows-xp-sp2-2000.aspx
Currently support status for Windows XP is at least XP SP3 and for Server 2003 at least SP2.
Please check your environments and plan soon upgrade/migrations appropriate to the lifecycles even more when you need to have long time consuming test scenarios on next versions of operating systems to ensure that you applications will also running properly on the next level ;-)
The same consideration should take place for your office client applications.
Just in short by the way ;-)
greets, Steve ;-)