Hi there, I hope you don't mind me moving your thread here so the other one isn't hijacked.
You can buy a replacement motherboard direct from eMachines
here but to be honest it is way overpriced and it is just a standard socket 478 motherboard. It also comes with a
PSU which you don't need.
There is one on newegg at the moment for $19 Open Box:
Newegg.com - Open Box: BIOSTAR P4M80-M4 Socket 478 VIA P4M800 Micro ATX Intel Motherboard - OEM
One problem you may have is that you will possibly have to reinstall windows, which the eMachines reinstall disk will be useless for, you'll either have to try and work around it (which may or may not be possible) or buy a windows license.
I hope this answers your question and feel free to ask for any further help.
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