If you want to play crysis flawlessly, then you are looking to spend some serious money on a graphics card. I would recommend you look at the nVidia GTX range.
1 GTX 295 will give you very good performance in crysis but at a high cost. You could also look at using 2 GTX cards and SLI'ing them for extra performance (requires a supporting mobo).
ATI also offer similar cards.
^Wrong again. GTX285 SLI will do better. GTX285 Tri-SLI is better but too costly and not worth it.
Well, GTX 295 Quad SLI is faster in crysis than the GTX285 Tri-SLI.
Here is a benchmark with GTX280 Tri-SLI vs GTX 295 Quad SLI. As you can see the GTX 295 Quad SLI is 17% faster than the GTX280 Tri-SLI.