I'd checked with Symantec, McAfee, CA, Panda, Kaspersky, Avast, F-prot and Eset, and none of these companies could offer a Windows Server anti-virus client at a reasonable price. All of them demanded that you purchase a 5-10 user license pack for $250-500+ per year.
No. freaking. way.
But I'd forgotten about AVG. Most people only think of AVG because of their free anti-virus (which doesn't run under 2000 Server). But they do offer a 2-user business license for only $83 for 2 years. Now TWO licenses I could actually use, I'll just give one to my SO. He had been running the free version of AVG, but the pay version has a few extra features (and I paid the extra $20 to get 2 users/2 years of anti-spyware as well). That comes out to just $25 per user per year for anti-virus and anti-spyware. Not bad at all.
And I can keep running Windows 2000 until Microsoft finally stops providing security patches.