| Lots of OEM installations require authentication (if they use an
| install disk instead of an image)

They don't use a disk. It's pre-installed
and locked to the BIOS. It's rare to even get
a restore disk anymore. Most just have a
hidden partition for restore. The OEM license
specifies being limited to a single machine.
Not providing a disk helps enforce that.

| and the installed Win* may well be
| an upfrade purchaced retail, or a total new installation purchased
| retail.

That's possible. He says it has a Vista sticker
but that it's running Win8. He may just be
misquoting the message it's giving him. I could
imagine someone shoehorning any old Win8
onto the laptop with no possibility of ever
activating, only as a means to get it sold. Most
people would consider Win8 better than Vista
because it's newer.