I have a ATI 6950 running 840 MHz , Mem 1325 MHz little voltage boost from 1100 to 1150 and keeping cool at about 140deg F. My hash rate on GUIMiner and the default slush's pool miner drop down with all the DDoS attacks been running right at 271.4 Mhash/s consistent. I too am working on getting more bang for my buck.

Just now trying to find a decent electric usage app