Ok, I know this maybe pointless and all, but take your computer to a pc shop ( not that ****ty geeksquad).
Ask them to a mobo test to see if the mobo actually has died which I am guessing to be the case.
They will probably charge you between 15.00 - 35.00 total for the test.
If it's dead then maybe it's about time you look into a new custom built pc.
It shouldn't be that expensive, you can build a good AM3 system for under 500.00 depending on your needs.
Or be like Soulphire and spend your last grand for a nice but expensive good speedy core i5 or core i7 system.
Really the choice is up to you, atleast you have a spare pc to use right ?
Why not save money between now in the middle of august and get yourself a good pc.