Bryce over at Technibble has posted a quick guide to show you not only how to keep an eye on your CPU temps, but what the max temp of most of the common CPUs are. Handy table to reference.

"A lot of users frequently ask if their computers are running too hot and want to know their maximum temperature for their CPU is. This article will show you how to monitor your processors temperature and tell you the maximum CPU temperature your PC should be running at."