Everyone recommending Intel seems to have missed the point; he already has an AM2+ setup. It depends on his specific board, but I'm fairly sure that the AM3 processors will be backwards compatible with AM2/AM2+ boards, so upgrading to a Phenom II would be the cheapest and, in my opinion, most efficient upgrade. That being said, if you want performance, OP, and are willing to pay more for it, definitely go Intel.