common fault with a lot of these emachines tim, I've replaced 13 motherboards in them in the last 6 months.
They use pretty generic motherboards , not really a problem to replace it, just need to know the overall spec , or the model of the motherboard, worst case just the board layout and onboard options etc.
easy to source you one, but be carefull going down the ebay route , you can get a whole heap of probs to be honest.
drop me a line if you need one cheap.
Robin