If you're a gamer you would really benefit from a HD 4870 GPU upgrade. I have a lowly Opteron 185@2.88Ghz and installed a Diamond 4870 yesterday to replace my 2900XT. It is 2x faster in all my games with AA and AF cranked. Without AA and AF its over 2x faster than my old 2900XT. Since you have a 3.5Ghz X2, you'll see your biggest gains from a GPU upgrade. It will definitely tide you over until you can get your hands on an SB750 mobo.