LinearHD
Rising Star
You can have a Nvidia and an ATI card working in the same rig, I'm not sure how to configure it but I know you can because I have read of people doing it so they can run a really good ATI card and a cheaper Nvidia card for physx its called hybrid.
That sounds AWESOME, I'll be looking more into that as I own an old GTX460, but my new rig is gonna have an HD6950, would be good to have those in so called 'hybrid'