You have 320mb. It's not bad, but it could be better as there was a 640mb version. Both those cards only have 96 shaders so they will perform worse than the 8800GTS 512 as that version has a full 128 shaders. If you want to play Crysis 2 you may experience a good bit of slowdown simply because 320mb isn't enough RAM so the system will spend a good bit of time swapping data in and out of the card even on lower settings.