Which graphics card would be better?

Well. I have been a Nvidia user for a while now, while my friend used ATI. After we built our computers however, he was forced to switch to Nvidia. ATI's drivers are very poor, and while they may offer a better performance, they tend to not be compatible with pretty much everything. Nvidia offers great cards with great drivers. I personally would recommend the GTX 260. Very good, and dependable card.