Will Avid Xpress Pro work with an ATI 9600 card with 256MB DDR? Looking at the minimum specs on Avid's site they only list Nvidia Quadro cards as compatible.
More likely than not, you're better off sticking with Avid's guidelines. Xpress Pro is a pretty specialized piece of software and is coded for specific hardware. That doesn't mean it won't work with other hardware, but you're not going to have the same level of performance.
At one point I built a PC for Avid with complete disregard for their specs, and I came to regret it.
For what it's worth...I use Avid 3.5 with a 9700 pro card 128 and the only diff with using nvidia cards is that you can't take advantage of the OpenGl that nvidia has. But my card has OpenGL capabilities also. I just won't be able to see as much 3D effects when using Boris or other software. Too me it's not worth the price to go out and buy another card. Especially when the Quadros are more downgraded server workstation cards. Your card should work fine for video. Not to mention Avid only authorizes Nvidia and Intel setups..but doesn't mean people with AMD and ATI can't do any editing on their programs since a lot people do use AMD and ATI in their systems with much success.
Again, for what it's worth. But if you're running 3.5 you can get away with a lot more. Xpress Pro and esspecially Xpress Pro HD is much less forgiving. You can check the Xpress Pro forum at www.avid.com and read up about certified systems vs. non-certified systems.
I have Xpress Pro 4.6 set up on a system with an Althlon and a 9600 Pro and it works perfectly. I upgraded to Xpress Pro HD and immediatly started saving my pennies for a Dual Xeon with some type of Quadro card.