On the other hand, one way to deal with that is to keep the machine cool enough so that the fan never comes on.
Right now, I'm using some blue cooler blocks, the kind you freeze and then stick in a portable cooler. I have three. One of them sits under the PowerBook, and the other two I leave in the freezer.
When Temperature Monitor starts to report that the machine is running too hot, I swap the warm block out for a cold one.
Low-tech, and very cheap, as long as you have a freezer handy. Seems to be working okay.