there is a colussal difference between 512mg and 1 gig. my friend has a modeeratly high end system (amd 2800+, 512 pc2700, 9800xt - 10x2 res ultra hihg, 2aa/16af). The game was very choppy at times and the loading took a good minute or two. Now that he got an additional 512 stick, loading takes like 15 seconds total and the game runs alot smoother.