Vid chip--I have a NVidea GeForce 7600 GS--I think it's doing pretty goood, not sure.
The 7600 is a good card, but you can't fold off it's GPU. Stanford has a new client that allows you to use your GPU to process WU's. When I first read about it, I was thinking "Hey, for a few bucks, I could throw a new card in my box, and double my output". Well, it's not quite that easy. Unless it's an idle box, or you really have a reason to take the pressure off your CPU, IMO right now it doesn't seem like a good idea, because your replacing your CPU, not adding to it. This whole deal is still Beta though, and I'm sure it will only get better.