I had a bad experience upgrading from windows 7 to windows 8.
I bought a laptop that had windows 7 in it... but it came with a $10 upgrade to windows 8.
so I grabbed the $10 update and installed it on the laptop. 2 years later I replaced the laptop with an SSD.
I went to install a clean version of windows 8 and use the Serial I bought from windows and it wouldn't work.
I called windows tech support which was very fast to be honest

. (a funny dig yes

).
anyway, they informed me I couldn't use the serial on a clean install, it only worked as an upgrade from windows 7.
so I had to install windows 7, then install windows 8 in the form of an upgrade.
so stupid. I will never use Microsoft again, im switching to..... well I guess I will use Microsoft again

.
there's really nothing else...and they know it.