How does a PC know it had a power outage? Is there some flag set somewhere?
Is it possible to shut down a PC in a neat way and fool it into thinking it was shut off by a power failure too? That way you don't mess up the OS and harddrive(s) too much.
Most of the newer PCs can be set up in BIOS to come on after a power down.
Go into your BIOS and look around for something similar to that ( I cant remember the exact wording).
To get into BIOS (or SETUP), when the PC is booting, and you have the black screen with the memory, hard drives, etc listed, press F2 or DEL to get into the BIOS setup screens.
If you have a splash screen pop up on bootup instead of the black screen, (such as "COMPAQ"), look for a message that tells you what key to press to enter setup.
You got to hit this key before windows starts to load.
After you set it up and exit BIOS with save, test it by just unplugging the PC from the wall after it gets completely booted, then plug it back in after a couple minutes.
If you can set this feature in BIOS, the computer should boot back up when power is restored.