MSI afterburner can only increase voltage for reference cards. The best combination is SDK 2.4 + modified phoenix kernel. Mining with CPU is a bad idea, you'll use more money (electricity) than you generate.
Hey Grue you seem to be a very sharp guy here. Can you tell me briefly what the 2.4SDK does? I have it installed, as well as the latest catalyst drivers. Do you have to do anything else to get SDK to work? Or is it used in place of the regular ATi drivers? Or do you just run something in SDK to tune the card/overclock?