So you are looking to rebuild a Windows 7 machine using an OEM licence but have lost / didn't create the OEM recovery media?
Or you want to do a clean rebuild using an OEM key without the bloat ware, silly partitions etc?
In short, yes you can!
Within a few simple constraints, I got this info from an MS MVP and have tried it myself, there are a few simple caveats;
1/ OEM Key and retail media must be of the same edition Home Premium OEM key works with Home Premium retail disc etc.
2/ You will have to do the phone activation using the automated system.
3/ You are of course re-installing the OEM licence on the machine it came with arn't you?
I have only done it once as I generally don't have OEM licences, but using a Win 7 home premium (non SP1) retail DVD I reinstalled the OS to an Advent Roma laptop without a hitch.
Hope this helps somebody.
Anyone else tried with different versions please feel free to comment.
