Ok... I have a late 2009 15" Unibody MBP. My friend has pre-unibody MBP (still accessible to battery and silver keys). Not sure the year in which his was released. Anyway, long story short, he tried to install Windows and failed miserably, effectively wiping his OS X partition out. He doesn't have a OS X install disc. I tried using my OS X disc in his computer and the language menu comes up and after that, it says "Mac OS X can't be installed on this computer." Any ideas? Need to get this fixed for him ASAP.