If I was you I would stick with what you have, but since you are asking about upgrading you must not be happy with current performance. Could you buy a second 6950 for crossfire? That wold be the easiest upgrade. If you want to spend all $1000 then you could get a 3570k/extreme 4 and a 7970 GHz. Your ram/psu/HSF/case and hdd are good. You could also throw in an ssd if you wish.