There is a setting on the BIOS that lets you turn on your PC with a press of a key.
Similar to this
http://www.tomshardware.com/reviews/...rs,1126-8.html
wait.. you don't have a main switch on the PC? like an Automatic Voltage Regulator??? If you don't want to turn it on accidently just shut down the main switches or unplug the main cord