I currently have single channel DDR2-800 running in my computer. You guys have convinced me to upgrade to Vista Ultimate 64 bit! I'm getting my GTX 260 Core 216 in a couple of days. Should I get 4GB of DDR2-1066 RAM? Or, just add 2 more GB of DDR2-800. The 800 would be cheaper I guess. How much of a performance difference will I see between the two? I won't be overclocking to anything more than 3.0Ghz for everyday stuff. I leave my Q6600 at 2.4Ghz stock speeds most of the time. Don't really need it overclocked. It does fine on stock speeds.