The application would be gaming.
The OS is XP.
Mouse is a Logitech G5 - not overclocked but it does have the heaviest weights in it.
Monitor resolution is 1920x1200.
You should be fine with 2gig RAM with XP. I only have 2 gig DDR2 667 with Vista 32bit and I do fine. 64Bit Vista, you should jump on 4gigs of RAM. By the way, I am curious, is your Q6600 running stock speed with that GTX 260 video card? I am curious because I am planning on upgrading my 8800GT card to a GTX 260 with my Q6600 running at stock speed.