Nvidia is one of the main companies behind Crytek and its Crysis 2 game, they had a chance to get it early and test some of its own graphics cards on various settings and resolutions. It looks like optimisation done by Crytek has paid off so you'll be able to play it quite nicely at 1680x1050 and medium settings while running the, now quite old, Geforce 8800GT graphics card.
Nvidia ran the benchmark with 8800GT, GTX 260, 460, 560 Ti, 570 and the 580 paired up with Core i7-960, 6GB of DDR3 memory and Windows 7-64-bit OS. The 8800GT was enough to score just above 30fps at 1680x1050 on medium (Advanced) settings.
Hardcore settings are a different story and if you want to run the game at those settings and at 1920x1200 you'll need the GTX 460 at least. At the same time, the GTX 570 is the cheapest card that can run over 30fps at hardcore settings and at maximum 2560x1600. At 1680x1050 the GTX 260 is quite enough to get you over 30fps at hardcore settings.
You can check out the full test lineup here