So OEM-Gateway problem, and also CPU?
How about this idea:
1) Purchase a new OEM win7 disk from directron for $100
2) Install it to a new hard drive
3) put that in PC #1
4) transfer the drive to PC #2
(PC #1 is an entry Gateway. I don't know if it is OEM and tied to the mobo or not.http://www.newegg.com/Product/Product.aspx?Item=83-113-188