If you want to max out the game, you'll need a dx11 card because the only dx10 card even with a chance of having the performance to max crysis 2 (although without dx11 features it may be fine) is the gtx295

But ya, there's no reason to upgrade just yet (although soon would be good), If you're on a last gen dx10 card (hd4/gtx2) wait until the next generation of cards in autumn, if you're not (8/9 series or hd2/3 series) then for the love of god get a gtx460 at least