Putting together a new system. Looking at the GTX580 for video card. I know it's not a supported card for CS5, but looking at the benchmark test, it's top of the list. Over the GTX 470, Is the extra cost (double) worth the performance? Considered one of the Quadro cards, but wouldn't mind keeping my cost down where I can.

And recommendations on memory, or brands to stay away from? Want to max out at 24gig. Looking at buying 2 sets of triple matched ram.

Thinking i7 980x six core processor.

go i7 980x; you wont regret it.

Skip the quadros; you can get almost the same performance for less than half the price with the 460/470; heck, even the 240GTS with 1GB DDR5 is a damn lot quicker than software.

whatever you decide to do, the CUDA 'hack' (which is more of a cake-walk; hacking entails actual code work IMO) is easy and works great.