Well first off, yuh running 4GB of ram on a 32-bit OS, which mean yuh wasting about 600MB of it. Secondly I/O is the bottleneck of PCs now. I suggest getting the latest game patches (sometimes its the game), also consider turning down the graphics a little depending on the game. Also check what services are running when you experience the slow downs. Do you have an anti-virus that runs in the backgound, for that matter what security software are you using? It's hard to say where your problem may eminate from without more details.
