The problem is, if you have an Oem disk for one computer.
It can setup a machine with the set of drivers for the hardware in that machine only.
If the hardware does not match. Installation of the Os may halt.
Oem is meant for a specific hardware setup.
And often the disk or setup is tied to that machine and its fitted hardware.
If your friends computer still has windows 7 on it.
Then press F8 to enter the extended windows boot options.
Select safe mode.
Once windows has loaded go to system restore.
You can choose a point as to where windows was first installed, that will clear all the garbage out.
Or you can select a system image if it exists on a hidden partition of the drive if none of the drive has been formatted. That will hold the Oem image for that computer and hardware setup.