depend on you use motherboard chip set, if use intel chip set i suggest for you nvidia graphic card then if use via chipset i suggest for you ati graphic card
I bought an Nvidia 8500 GT when I built my computer. That was a horrible MISTAKE. I should have bought the 8800 instead
NVIDIA has come out with a new dual-gpu card http://www.techwix.com/2010/11/23/nvidias-dual-gpu-card-unveiled_4