RAM size on a video card is a very poor way to measure performance. A 256MB GeForce 6200 is going to get wasted by a 128MB GeForce 6600GT. The quantity of RAM is going to do more for smoother performance than the speed. You can use DDR2-800, but unless your system is using the faster speed, you won't see anything from the higher speed. It's only going to operate at a set frequency in conjunction with your FSB. You will see an improvement (depending on what you play and at what settings) by going to 1GB from 512MB, but that's contigent on the system making use of the extra RAM. If you're still playing Half-Life and not FEAR, you're highly unlikely to notice much of a difference---if any at all. This, assumes of course, that you have a decent video card to play the game with. You can have 32GB of DDR2-1066 RAM and a GeForce 2 MX and guess what? FEAR will still run like crap, and it's not because of the amount of RAM. The video card isn't able to process that heavy of textures due to the lack of pipelines to do it with.