I once had a PC that burnt out only one of the voltage lines in its power supply - the PC went dead as you described, but I seem to remember there was an LED on somewhere (it was lit by a different voltage line than the one that burnt out). A PC power supply supplies voltages at several different levels - from memory they are +5V, -12V +12V. In my case the +5V line was ok (I think this was the case), but the -12V line was the one that burnt out. Just had to replace the power supply and everything was fine. You might need a multimeter to see if this is the case on your PC - i.e. by actually measuring the voltages coing out of the power supply.

Dreams are just nightmares on prozac...
Digital WasteLanD