A friend was faced with an interesting problem. They tend to fall asleep listening to music on their Windows laptop, but hated leaving their machine on while they slept. (rundown batteries/higher power bill/etc...) They wanted an elegant way of shutting down at a certain time each night - with the ability to override if they are still up.
I suggested they use Windows Task Manager -- after the blank stare, I went in search of the best way to explain it. This blogger did the work for me, and did it well so I'm sharing:
How to Automatically Shutdown your Vista machine How to Automatically Shutdown your XP machine