i ahve bu i didnt see anything printed by microsoft that says that they would take up more if more were running, right now the cpu will be at like 3% when working on word prossing and 30% when loading a office program, and PF usage is about 76mb all the time
if you have a newer intel penium 3 or 4 chip, you will have speedstep technology. see control panel-system-computer, it will tell you the processor frequency and the usage at the moment. the best way to save energy on a laptop is: keeping the hhd from spinning (under power management, and by having lots of ram) and by turning your lcd screen dark, the brighter it is, the more energy you use. any programs that run in the background are peanuts compared to those two things.