Looking for Mac Pro owners who have ran a mix of cards inside OS X, not worried about boot camp issues as I run Fusion for whatever is needed. I got a new Mac Pro today with the GT 120 and have a 3870 coming in tomorrow and a 4870 on way in couple months almost it looks like. Anyway how do ATI and NVIDIA work inside OS X together ? Whichever monitor has the window on each card open is using that GPU I take it ? Any issues or certain ways to use when you have a combo to get the best benefit from each ?