@ Kornelax: How far into the future are you looking and what are the rest of your system specs? It is all very well saying the HD58xx is the best choice, but it'll be wasted with a low or even medium leval CPU.
Also do not discount the 'current gen', a HD4870/GTX260 (or GTX275 if you want more power) are still fine cards and although DX11 may be the next thing, DX9/10 are going to be around for some time to come, far, far (in computer terms) into the future.