Well I just formatted and put win2000 back on and it runs smoothly know, where I used to be really slow loading CS maps to get on a server, now I'm always in first.
Now a days you need to manage your pc very frequently, adware, spyware, "leechware" -> shares your recources over the internet. virusses etc etc. Get a fire-wall -> less memory, get a anti-adware -> less memory
So you really need a lot of memory today.