I have a 12" Powerbook G4 1.5, and the fan is almost always on. Literally, the only time it shuts off is if i close every program. I've gone into the task manager, and i have no extra programs running in the background, I don't even have any Dashboard widgets running. And yet the fan continues to run. I don't expect it to be off all the time, but it would be nice if it didn't get really hot, and it would be nice if i didn't have to listen to this whirring when i'm doing something as simple as reading a page on Safari (that was loaded 5 minutes ago) Hard disk botomside is 112~ and processor topside is around the same, usually a bit lower.