fraps just monitors framerates.. it doesnt benchmark programs, but can help you collect results.
btw, look around anandtech, hardocp, xbitlabs or any other hardware tech site for 6600gt benchmarks and i'm sure they've benched the card with SC/PD as its a fairly recent/demandind game.
one thing to look for at the benchmarks, is whether it has 128/256 ram which will affect price/performance. also make sure you get the right card for your system (agp/pci-e)