I'm using a mid-2009 MacBook Pro which I decided to install Ubuntu on without dual boot. I thought I'd just give it a try and see if I liked it, but I don't. I'd like to install another OS, but I can not seem to figure out how to boot from a disc. I hold "option" at startup and see EFI disc only (no matter what's in the optical drive). When I click on the EFI drive, I get an error message telling me that it can't find system boot order, and that it's reverting to defaults. It then boots Ubuntu.