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.