Core 2 Quad and Duo Temperature Guide http://www.tomshardware.com/forum/221745-29-core-quad-temperature-guide
wolf, your temps are great, especially with the stock cooler. However, if you are going to overclock, you will need better cooling.
elrodvoss, your temps are too high. My Q6600 (OC'd to 3.6 GHz, TRUE HSF, Antec 900 case, Vcore = 1.425 volts) runs 61 C to 66 C under Prime95 load.
I pretty much follow Intel's recommendations for voltage and temperature limits. I have the temperature alarms on my motherboards set for 70 C.