What is the best graphics card for gaming, for around $400 - $500?
At that price you are looking at a AMD 7970 or Nvdia 680. They are much the same so it comes down to personal preference, If you are doing a multi monitor setup, go with AMD, there eyefinity technology is more developed than Nvdia, as there cards come with 3Gb or RAM stock while Nvdia comes with 2Gb.So...If you realy have no preference towards either card then just get whats cheaper or looks cooler.
Other options are a GeForce 670 which could save you some cash (they are clockable upto almost the 680 performance)
The 7970 is very clockable aswell so push that to the limit and it would be better than the 680 (the 680 isnt too great at OC apparently)
If your just gunna use it at stock with no messing around then isteelsolz is bang on.