Having recently joined the PowerBook club I have been researching options to avoid burning my lap . During the search I came across a program called ThermographX (http://www.kezer.net/shareware/thermographx/). It displays and tracks the heat of your unit and can also graph it for you. An interesting feature of the program is that other users have submitted their results. That allows you to view them for comparison with your laptop. It is shareware but you can download and try before you buy.