By the way, do you know of any good message boards or support sites other than experts-exchange that don't charge you to ask questions.
If there is a memory leak, task manager sure isn't showing it. The processor is staying at 99% idle and it shows there is still over 250 megs of free system memory, I just checked it this morning. I found an article that says winXP stores portions of its OS on the pagefile after being on for a while and that this can slow things down, there's a registry tweak to disable this that I'm going to try out today.
and we run spybot on all machines.
No, Win2K was a replacement for all business OS's which primarily was Win98. The reason most home users didn't switch was because of software compatibility. That's still the main reason reason for people to hold off on Windows XP today, they have a Norton 2001 or Easy CD 3.5 and don't want to spend $150+ to upgrade their OS.