There is a small cheat for Expertool to work peramnently.(I expect u to b daring). This involves Video BIOS flashing. Get nVflash and NiBitor bios editor from MVKtech.net download section.
U need to boot in DOS, go to the directory where u extracted nvflash and type "nvflash" to see the complete list of cammands (as I don't remember them right now
)
first backup ur bios and then edit the bios using nibitor. change the VGA card maker company to Gainward. and the reflash it using command
"nvflash --overridesub biosfilename.rom"
now install gainward special drivers and expertool. and see how nicely it works. one thing more there is no risk involved here so u can do it nicely. expertool can increase the extent of overclock as mention by other ppl