Dude, here. Speedfan. Simple.
http://www.almico.com/speedfan.php
When checking temps you just look for the highest number and that'll be your CPU temp. Um, also. Check this. The more AS3 that you put on the worse it will cool the CPU. More and more acts like an insulator and actually prevents heat flow. Your best bet its to clean it off, and put a small dot on the CPU and spread it thin as one or two sheets of paper. Or better yet, ditch the crappy and messy AS3 for some radio shack grease. Works almost as well (there was a review of like 20 grease and it was one of the best), you get like 3 times as much, and you could clean it off with your finger cuz it's so easy to remove.