check out my post. I was also having problems with Q6600 g0 but now I got it running at pretty much 3.8Ghz stable.
I ran my Prime95 tests for a good 10 mins, then 15 mins, then 30 mins all without crashing or any errors/ failures.
Heres my post, complete with my screen shots etc.http://www.overclock.net/t/1313568/solved-with-solutions-bsod-need-help-after-overclocking-q6600-g0
Though you should note that just because it works for my setup and chip, doesn't necessarily mean it'll work for yours.
You can use mine as a rough guide and then play about with the voltages.