how can I auto-restart after power failures?

I'm running WinXp pro on a PC with the following specs:
Gigabyte GA-8INXP MB, P4 2.4ghz processor, ATI Radeon
7500, 2 WD 160GB HDDs in RAID1, 512mb PC2700DDR. Power
supply is 400W. I have several video cameras recording
onto the drives. I would really, really like the system to
restart itself if the power goes out & comes back on,
without me having to be around. I've checked settings in
the BIOS, ACPI is enabled, and it's supposed to fire back
up, but doesn't. Any inspiration out there?! Thx, Jimbo