Comment Re:Shame about intel mac pros (Score 4, Informative) 134
Current versions of Mac OS X require 64-bit EFI. The original Mac Pros only had 32-bit EFI. Mountain Lion does not have a 32-bit kernel and will not load 32-bit drivers in kernel space (kexts). If you replace the graphics card in the original Mac Pro with one that has a 64-bit driver, you can install Mountain Lion on the original MacPro1,1.
See http://www.jabbawok.net/?p=47 for instructions.