6600's are like a frigin furnace. Those temps aren't overheating for a 6600.
He never gave temps. He said where he's living is getting up to 80-90F which would be a really good temperature if the card was running at because that's 32C at 90F.
Also, the warning alarm is set to 120C or so by default, but I can tell you the card would stop functioning long before it actually hit that. I don't think I've seen anyones card going above 100C and still working normally. We did have a guy from the UK here at the forums who's card was hitting 100C I believe though. He got better cooling for it and just didn't put it under load when it was hitting up that hot.
Use that to enable temp monitoring. Not all cards have it on by default. I know evga had theirs turned off.
Use a program like rivatuner to watch temps. It'll run in the background but if the game is freezing up and causing the whole computer to lock up and you have to restart then it won't matter if it runs in the background cause you'd never get to see it.
If you're able to CTRL+ALT+Delete out of the game when it freezes then you can run rivatuner and let the temp monitor stay up while you game.