I've heard that you get a lot of bang for your buck by going SLI on the GTX 570. I'm running a slightly overclocked card with stock cooling and temp alerts at 80C (never been over 70C) and it is actually running CoD without the patches at an
acceptable framerate! There's still microstutters, though, which the patches and mod fixes! Now I get silky smooth gameplay with 1 card and everything on high over the ocean, and some slight FPS drops over land
Can't complain, though I want the second card for SLI soon