How does that "latch relay" business work for the on/off switch?
Here is a simple drawing of a manual-on, auto turn-off power switch I build using a single coil +5vdc relay I found available on e-bay. You press the switch to turn on power and the first instructions in the processor is to turn the output pin high to latch the power on. When the program wants to power off, it just takes the output pin low.
http://img25.imageshack.us/img25/563/08miq7.jpg
Lefty