its not really 'illegal file sharing' if its my [censored]
look on it like this:
i put my Windows OS for download (free), and my friends can have it (or anyone else), but it is MINE and i PAYED it and they will have it for FREE with MY licence which I payed with MY money
so basicaly they will have it without any original licence which will prove that downloaded Windows OS does not belong to them :P