Depends on resolution for crysis, 7950 GX2 1280x768 at medium/high details (bottlenecked by cpu, can get it on high with a oc'ed cpu). You don't always need new cards to game with, personnaly id use craigslist or ebay and find a good graphics card.
Geforce: 7950 GX2 = $120 average on ebay/craigslist
Geforce: 8800 GTS 320/640 MB = $100-$120
Geforce: 8800 GTX = $150- $200
Find 2 of the above same model sli it and you can max your crysis while saving a little bit.
What the hell? 7950GX2 for Crysis? and the 8800GTX under the $200 range?