What kind of processor do you have? More importantly, what kind of screen do you have for that res? Any single screen solution that supports 2560*1600 I could find costs at least as much as an entire gaming rig.
Anyway, SLI 460s do rock solid 60 fps V-Synced at 1920*1080. If you get 40 fps at 2560*1600 that's what you can expect. Crysis 1 should run worse for you, so should a bunch of other games.
Splurged for a Dell U3011 (about half the cost of the rig from Digital Storm). Should hopefully be the last monitor I need to buy for a very long time. Processor is an Intel 930 (4 core, 8 threads). I won't buy two/three graphics cards. The speed at which Nvidia and AMD keep cranking out new cards, I just keep buying one of the latest and greatest and selling the old one on ebay for usually just $100 to $200 less than I bought it for originally. Besides, my office already gets hot enough with just one GTX 580.
I'm rather jealous mate... That screen is 1,375 Euro in my country.... I can understand your desire for single GPUs (I'll go this route the next time I upgrade myself) but I fear SLI/XF is the way to go in this performance class.
2560*1600 is almost twice the resolution of 1920*1080 (1.91 aprox) so you're in the very enthusiastic end of hardware. But damn, do I envy you..... If you're lucky, dx11 might actually improve your performance, at least if they release proper gfx options so you can maintain current setting but use dx11 mode. The gae could do with soe tesselation and physics imo however
If they use tesselation...then DirectX 11 is not gonna improve your performance lol.