PID (Process IDdentification) numbers are created each time a new process is started and automatically roll over when the maximum pid value is reached. So, you could only have 3 programs running with PID numbers like 190, 1043 and 50000. That number is really useless in itself unless you are killing processes by ID number.
What I'd be concerned about is how many processes are active. If your machine is bogging down, that's a pretty good indication that to many programs are running, or something is hogging resources. Or, something that you use frequently isn't releasing memory. Or you have a virus/spyware. I know, lots of "ors" but you haven't given much to go on.
By the way, having to reboot Win2K once a week isn't unusual. It was actually common in the server world. I don't know if it still is since I switched my servers to Fedora/Linux a long time ago.