I downloaded Windows Technical Preview, iso, which I understand to be the forerunner to Windows 10. (Ten, not nine.)Due to be the eventual replacement for the dog of a thing called Windows 8, 8.1, 8.1 Update 1 etc.
Put it on a spare partition (80GB), used unetbootin to do the job- no trouble.
Installed a few programs- all smooth so far.
Behaves pretty much as Windows 7 plus easy relationship with apps. Much more pleasant experience than my time with Windows 8/8.1.
Still has the ugly GUI though, but at least there is a Start Menu and it is quite OK.
Easier to get around the Microsoft Account log in than with the the 8.1 upgrade.
Screen shot attached. Cmd shows it as Windows 6.4, and it is an evaluation version.