To be honest, I found using nibitor BIOS editior v2.2a I backed up my BIOS, selected teh temps tab, unchecked the 6600 temp trick box.
I then flashed both BIOS and now I dont get that issue at all with temps - not sure how accurate the temps are though LOL.
On the overclocking issue thats never been a problem for me - just use rivatuner and disable the clock test, then all will be golden and you can watch those benchies fly through the roof!!
I am using these drivers for benching as they are FM approved which meand I get to go in the Hall Of Fame if my scores are high enough - which is agreat accolade to have and extra pimpage for my favourite site EPUK!!
Cheers
Mav
Enjoy.