I just saw someone asking for help at removing Conficker from an NT4 server. Extended support for that ended back in 2004 or thereabouts … with a lot of notice. That means no patches, no support and no security fixes for that operating system.
That made me think; When does extended support for W2K Server end? I looked it up and found the date for termination of extended support is 13/July/2010. That means MS will fix security issues until then. Normal bug fixes ended back 2005 with the end of mainstream support.
So if you have Windows 2000 Servers you should get planning. Talk to your application vendors and apply pressure for W2008 support. You’ll need new hardware or virtual machines because you cannot do an in-place upgrade. If you don’t upgrade then you face the risk of not only MS not supporting you but others as well, e.g. anti-malware or backup software vendors. Imagine not having a security patch that every other OS has, not having protection of your system and/or data and catching something like Conficker. That’s a pricey gamble if you ask me.