Question about running a graphics card as a capture card

I have 2 NVIDIA 275 GTX graphics cards each with 1792MB of video memory. I want to turn one of them into a capture card. Say I am playing Crysis. I run it at max settings and get 40-45 fps when my cards are in SLI and 35 fps when they are not. I use Fraps to capture a video of the screen and the fps drops to 2-7 fps even when in SLI mode. If I designate one of them as a capture card, I would expect being able to capture at 35 fps, though I have no idea how to do this. Do I need to download a different screen capturing program? If so, where do I find a free one?

2 NVIDIA 275 GTX 1792MB
Core 2 Duo 6MB 3.16GHz
128 GB SSD
8 GB DDR2 RAM Cas Latency: 4, Timing 4-4-4-12, 800MHz
OS: WIndows 7 Release Candidate

Thanks guys.

try modestly OCing your cpu and if that helps buy a good cooler and go for broke

the problem is the cpu, get a quad, disk is unlikely