Shouldnt be a problem, all will work fine. Win7 will use the right drivers. I've been experimenting myself with 2 different cards and all came together with each use. At the moment I'm having issues with Ati and Nvidia together. If your using one monitor and it has 2 inputs I would connect both cards to the one monitor just to lighten the hassle. Also remember to enable the one card before you disable the one your using or that would totally suck.