Windows On Mac Torrent?

Um, to previous answers, it is impossible to buy a copy of Windows. You only buy the license (or right) to use it, from Microsoft. Microsoft owns every copy. It's explicitly in the license agreement.

If you want to boot into Windows (which I don't recommend) using Boot Camp or something, just torrent Windows. It's not difficult.

I dual-boot OS X (which I never use anymore) and gNewSense GNU/Linux. Much more powerful than Windows, and guess what, you actually own your copy.