Microsoft is saying that the Windows 10 upgrade retains the licensing properties of the version it upgraded from. The problem is that when they continue to describe OEM, they are talking about system builder OEM (linked to specific hardware) and not manufacturer OEM (linked to the BIOS). Let us say I have three identical model Dell computers with Windows 7 Professional OEM. I can install Windows 7 on one and clone it to the rest, because the OS is based on the SLP 2.1 in the BIOS. But if I upgrade on of these Dell's to Windows 10, could I not clone that to the other two (and not break the license)? Or would that one Dell upgraded to Windows 10 be linked to the individual hardware of that single computer rather than the actual BIOS? It sounds to me like any Windows 10 upgrade of an Dell OEM Windows 7 installation would actually be treated like a system builder's license and would only be good for that specific computer and could not be cloned to other Dell's of the same model. This would mean that in the case of manufacturer OEMs, Windows 10 DOES NOT retain the license properties of that type of OEM, but instead uses the license properties of a system builder OEM. I'm not sure? Does anyone have any clear answers on this? Windows 10 just takes a long time to install. I'd rather clone it to several machines.