Both versions you've listed specifically state in their license agreements that you may not transfer the software from one computer to another unless a) it is your computer and b) you remove the software from the previous computer.
Can I transfer the software to another computer or user?
transfer the software to another computer that belongs to you. You
may also transfer the software (together with the license) to a
computer owned by someone else if a) you are the first licensed user
of the software and b) the new user agrees to the terms of this
agreement. To make that transfer, you must transfer the original
media, the certificate of authenticity, the product key and the proof
of purchase directly to that other person, without retaining any
copies of the software. You may use the backup copy we allow you to
make or the media that the software came on to transfer the software.
Anytime you transfer the software to a new computer, you must remove
the software from the prior computer. You may not transfer the
software to share licenses between computers. You may transfer Get
Genuine Windows software, Pro Pack or Media Center Pack software only
together with the licensed computer.
If you want to install Windows 8 on multiple computers, you must buy multiple licenses.
However, the key difference between OEM and System Builder (Personal Use, as pointed out by comments) is that OEM is tied to a specific computer, but System Builder allows you to install Windows on a device with no previous Windows licensing, a detail that you wanted, per your question.