Upgraded rig still getting lag

I have been upgrading a PC that I have had for a while. I have an eMachine E1161-05 motherboard type MCP61PM-GM. I put a Evga 650 ti 1gb in it. And four gigs of memory. Also, it has an AMD Phenom II 965 Quad Core Black edition CPU. I am running the rig on windows 7 (64 bit) It plays games alot better now with the new GPU. I used to not even be able to play Diablo 3 on it. Now it is very playable. Although I am getting alot of frame rate and lag. Enough to make the game not as enjoyable as I would like. I can barely run Team fortress 2 with just 16 bots... Any Ideas?? I plan to upgrade my Mobo to the Asus M5A78L-M LX Plus this friday.