Its a BIOS feature, it means you have to turn it on OUTSIDE of windows. When you start the PC up it will say 'Press ??? to enter setup'. ??? is usually DEL, F1, F11, and sometimes esc. try DEL first. Turn on PC, and press and hold one of those keys BEFORE the system beep. Should enter 'setup'. Look for Power settings, ACPI settings or somthing along those lines. You should find an option in there you can turn on. Then choose 'Exit Saving changed'
Never done it myself, but, thats how its done. The turn on though , i am sure, only works when coming back from a standby state, not a start from completely off. Have to use a power button for that. . . i may be wrong though
J