Windows 8

Nah, once it's been used to activate one computer, I don't think it's viable for another one.

I'm not sure how it's implemented though, it's about that stuff with "activating windows" and such.

I had to check this out yesterday as I'm migrating all my junk to a new PC.

OEM copies are 'married' to the PC they were originaly installed on. They will not work on any other PC.

Retail copies can be reinstalled on any one PC at a time but have to be reactivated every time they detect a 'significant' hardware change.
 
Windows 8 is horrible: slow, buggy, incredibly stupid--but I suppose they would expect me to pay to upgrade to their new pile of manure. I have just been letting a big nice Windows 8 laptop sit around while I use the years-old tiny netbook that runs infinitely better (with linux) than the windows 8 machine. POS.