Hub , about the most you can do is get 3200 ram and that 2400+ will OC to 2.1 on air cooling / 2.2-2.3 on water ...the ram helps but the overclock on it from 2.0 is pritty much unoticable and very little gain . you need a 2500+ barton cpu to start getting any gain ... but there so old now unless its near free its better to start saving for a duo core ect .
you should be playing AH deciently with your setup ...(unless your trying to push a lcd monitor to the max)
mrs roo's pc is the same as yours but with a 9550 256 card in it and it runs AH nicely 35 -75 fps on 512 tex, No preload and performance slider at about 2/3 rds up ...(tuned for 512 ram that it has so it runs around 380 mem used and doesnt go over 480ish total used in furballs)