Hi, I am having some difficulty in choosing the right graphics Card. I have been looking at the New Radeon 512MB 2900XT series and I got to say they have pretty good specs. But then again I Nvidia is also good. I have been using Nvidia on all my computers. I don't know which one is going to be better. The 640MB 8800GTS or the 512MB radeon 2900XT? If someone can help me let me know. I want your opinion. thank you