[BallisticWookie]

www.guru3d.com

go there and read all you like about the pros and cons of computing and hardware.
The CPU is the bottleneck of your system as SPF-15 said, you will see little change in performance if you get a GF3. You really need to upgrade your CPU before you buy a highend video card. You cant count on the GF3 alone to do all the work. The games will still more than likely have poor performance. You need a good CPU just as much as you need a good Video card.