Looking at a few sites, there is a lot of conflicting info. Some people say it seems to make no difference some say a lot. The general consencous seems to be that it makes it slightly faster, but hey even slightly is good, especially where intensive 3d games r concerned. If u want say 1gb id always get 2 512mb sticks of the same model so i can have dual rather than a single 1gb, my ram gets good scores in Everest considering its cheapy Value, and overclocks nicely too, not sure how much Dual is helping, but if you're going to upgrade id go for dual c ram.