I've been browsing the forums and community members have been suggesting OEM and full versions. I've done a bit of research, but I've only become more confused. I'm building a computer for my boss, and should his mobo die, I don't want to be on the hook for buying a new Windows OS.
What's the difference? Can I install Windows 8 Full on a brand new build?
Basically, the OEM version is going to be tied to that computer. I think they typically do this by tying it to the motherboard in the system. If you build a new system as an upgrade, you will need a new OEM copy of windows. The retail can be used again in a new machine, so long as the old machine is no longer in use. (Can't have two copies of the same windows at once.) As for functionality for the user, both will be exactly the same, and both can be used on a brand new build.
As for the motherboard dying with the OEM version, you may need to contact MS if the replacement is not the same.
With Windows 7, there was the retail version and the System Builder's OEM version. The system builder's version was intended only for those retailers who built and then sold custom computer with the OS installed. Home use was not supposed to be allowed.
With Windows 8 a new license agreement has been written: Windows 8 System Builder Product--Personal Use License. This is essentially the same as the Windows 7 System Builder's license agreement, but without the requirement to sell the system once built. Additionally, this license is transferable to another computer you own (can only be installed on one computer at a time), or to another individual (with you ceding all rights and privileges).
Even on Windows 7, while tied to the motherboard, and exception was made for defective or failed parts. So if the motherboard truly did die, it was transferable to a new motherboard for that same system.