I think you meant "Windows" vs "Mac OS" - PC is not an OS, and Mac OS technically runs on a PC. (Sorry, just a pet peeve of mine - Ubuntu user).
I would probably be a Mac OS user, if I could afford it.

As is, it's a large EXT3 formatted hard drive dedicated just for music and a backup USB EXT3 formatted external drive that I don't use as much as I should.