From my experience...
C2D's will just freeze/crash when it hits a really hard stone, so if you're worried about damage, don't worry too much... just don't go crazy on the voltages
I've gone high to around 65/66C before my system crashed before, so when I bench, I get it close to 65/66C on 100% load, on 24/7 use, I try to stay 61/62C on 100%load... let's face it, most people don't hit 100% load constantly.
I use Speedfan, Orthos, Prime95 (x 2), CPU-Z, CoreTemp. Since I'm a gamer, I use 3dmark01 SE, 3dmark03, 3dmark05, 3dmark06, Aquamark3. And because I have a ASUS board, I use ASUS AI Booster, PC Probe, nTune. For graphics, I use ATITool (even though I have a 8800gtx), Rivatuner. I also run FEAR 1.07, PCMark, so I can compare my system with systems published in magazines etc.