Unplug ypur box, open the puter and look for a jumper near the battery that said on the board "lr cmos" it will be a 3 pins connector, numbered 1 2 3 (duh!) and it will be a jumper btwn 2 and 3 (correct me if i'm wrong) what u need to do is switch the jumper to the pins 1 and 2... Wuala!! psswrd gone.
Close everything turn your puter back on, to the bios setup check the boot order and thats it!.
If It doesn't work follow netman's instructions.