Cali3350,
Benchmark Farcry using FRAPS at 640x480, 800x600, 1024x768, 1280x1024, and 1600x1200. Plot them with excel. The closer the line is to horizontal, the less likely your video card is the limiting factor.
You can also do the same thing in the resolution you play buy changing the GPU clock. If your average FPS does not move, then the speed of your GPU is not the limiting factor. Then try video memory, look for the same thing. After that vary the GPU AND video memory, again if your average FPS does not move, your video card that that resolution is not the limiting factor.
Hope this helps,
Dr. Ffreeze