Well I was working on 2000 Pro at work and it has been installed there for over 6 months now. And yes, I tend to do all the critical updates right after I install so I can be as protected as possible. But, at my workplace none of the updates were installed, but I could get to the update page and start downloading. I don't have the authority to download and install the updates, since I'm a student worker so I just leave it like it is, although I believe they really need to update all the machines.
At home I have XP Corporate and I immediately downloaded and installed all the latest updates when I installed it a couple of months ago.