EASY ... USE ATI TOOL set to max performance and save it as a profile ...
Then use the Menu given .. look for startup ...
Tick the LOAD DURING START UP function and TICK your prefered profile ...
THEN set start using SYSTEM REGISTARY ..

Then everytime you logon to windows ... it AUTO OC to the VALUE you SET ...

Ah .. one precausion ... make sure you do not run ATI CATALYST control panel .. it set you back to default ... for me ... i just dont touch it ... and use msconfig to close the Startup file on ATI control panel ...