What is your price range? What is your power supply? What resolution do you want to game at? What kind of motherboard do you have? These are all things you must tell us in order for us to give you useful advice.
Obviously, your current video card isn't going to run the game well. We can help you pick a video card that will run it, but we need some info first. The game runs much more smoothly than Crysis 1, so you won't need to get an uber computer to run it. (Of course, you don't have to have an uber system to play crysis 1 anymore either...)