OS X 10.11 El Capitan System Requirements:
MacBook (13-inch Aluminum, Late 2008), (13-inch, Early 2009 or later)
MacBook Pro (13-inch, Mid-2009 or later), (15-inch, Mid/Late 2007 or later), (17-inch, Late 2007 or later)
Mind you that's the unreleased OS X version currently in beta! And it definitely supports ANY MacBook or MacBook Pro shipped in 2009. And a lot of them shipped before then. (There was no 13-inch MacBook Pro shipped in early 2009.)
Furthermore your Mac doesn't support Win8 under bootcamp because the drivers that are included for your Mac model don't support windows 8. You can try to install it manually and then maybe you'll find up-to-date drivers for the hardware. It'll probably work, depending on what "unsupported" Mac you have but it's quite simply "unsupported."