I have the same problem with my MacBook2,1 (2GHz, 4GB Ram). The CPU is OK because I only use light apps, the laptop has a lot of free memory, but the temperature is very high and of course the fans go crazy even with just a few apps.
I have the 10.6.6 version, I've made a fresh install and the fans are clean. I must use a lot of websites with flash content but I also use click2flash
