For those looking for a truly free Win10 installation:
http://www.zdnet.com/article/with-a-...tag=TRE17cfd61
Short-n-sweet:
1- join the Windows Insider program.
2- install iso version before release (July 29)
3- get legit version for helping test the beta.
Maybe.
(Depends on whether the techies or the lawyers get the final word.)
Full details at the source.