Dual Video Card or Better Video Card? W/ Dual Monitor
 

Hi, I start doing some video editing and Just notice in my dual Screen Setup that the 1080p video don't run smooth, I did a test with a single monitor and the video run perfectly, so my question is what is going to be better for me: dual Video Cards 2x 9800GTX or a Better Card like the GTX 285 or 295? BTW I runing OSX LEopard

Use only approved video cards for the current version of OSX you have. As far as I know Apple writes all of the video card drivers for OSX.

Increasing the number of GPUs on the machine will only enable you to drive more displays. It will not give you any more computing power to edit video.

Until snow leopard comes out, use only 1 gpu.