9800 GT is not good for gaming. i would say 3 Ghz duo core won't bottleneck your 9800 GT .
First of all, your window is VISTA. Vista alone take 1 GB of your RAM. You have only 1 GB left to play game. Which game were you playing? FPS game release in 2009 +? you need a better graphic card if you lag when you play game and extra memory .
Actually it's two 9800gt, so that is the equivalent of around a gtx280 IIRC. I agree that an extra 2gb of RAM would benefit you.