The only Free OS is Linux.
Hello,
Okay fine. the only free distributed OS is Linux. There are things like ReactOs that is more Windows based but it is still in Beta and does not support much hardware. Same goes for Haiku. You can get Windows for free but we do not promote that kind of action.
As for a free license to use it. Linux is the only real one. Haiku and ReactOS are still more Linux based than Windows. So unless you know others, i am not wrong. Wtih staying within legal limits.
Cheers,
Mak