X-12(the annoying camera add people) have some remote control thingies that will turn outlets on and off. Assuming the BIOS of the PC supports the "power on after power outage" feature (or something to that extent) you could have the outlet turned off and when you hit the "ON" button on the X-12 remote, it should make the PC fire up.
THe X-12 packages that I've seen use a remote control to activate the power switches.