I run W2K when I just need another offline copy of Windows for a while -- no license requirements. And I have a 10-yr old 800MHz Pentium-3 laptop with 256MB RAM that runs W2K perfectly well, and I use it from time to time to this day for light websurfing while exercising (it's strapped to the stationary bike).
But for serious online work I use Win7 or XP.
For serious work? I find no difference between Win2000 and Windows XP or Windows 7 for that matter as to getting work done. Now maybe some of your programs actually specify a more modern Windows operating system, but I have not seen that (Win 2000 or later). After all, they try to insure that Windows programs need a particular operating system (for their benefit) but does it really? Most programs work just fine with older systems.
I can understand security as a precaution for using a more modern operating system, but really, unless your connected to the internet (with no firewalls or anti-virus programs), does it matter?
Most user programs require specific processor capabilities and ram, not the latest operating system. They just do not test on older systems...