That sucks dude! :-/

I'm going to have to say it's the processor, since you said the motherboard powers up with the CPU plug "unplugged".

You may want to order a "cheapie" motherboard to get you by, in case it's the motherboard instead. Now would be a perfect opportunity to upgrade processors if you were even remotely thinking about doing so.

((( *edit*: I meant order a cheapie motherboard at the same time you order a processor, so you won't be out of commission for another 3-4 days while you wait on a motherboard to arrive as well. )))

Or even a Core i7 setup. Everthing else you already have should be compatible... (well, except your memory)