well that is not a very powerful card so even 512MB wouldn't hurt it at all. It also doesn't come in any other flavors than DDR3 for the memory (another reason having 1GB of GPU ram wouldn't do much). I have a GT 540m and even this card, I don't think, would benefit from that much ram. A card like that would probably run your game at or around 25-35 FPS on low-medium settings at a low resolution. (1366x768, or 1280x720, given the DDR3)