Well, I had a pleasant surprise, and I just thought that I'd share it with everyone. Last night I ran System Optimizer X, running both the optimizer and the system cleaner. Then, lo and behold, after restarting my system, my PowerBook started running much cooler than it had been. The fan wasn't running as often, and my wrist wasn't getting as hot sitting on the wrist rest. I must say, I am fairly impressed by this. Maybe I should do system maintenance more often?