Currently Being ModeratedNov 19, 2012 12:02 PM (in response to jfritchman)
Mac Pro models before the 2008 models have an EFI-32 firmware version so old, Apple has decided not to update it to EFI-64. (there may not be enough space in the control store to update it easily.)
The newer Mac OS X 10.8 version also requires a newer graphics card and MUCH more RAM memory, which is frighteningly expensive on these older models.
If you need a major RAM upgrade, you could sell your old Mac and buy a 2009 or later model, add more RAM, and still come out ahead.Mac Pro (Early 2009), Mac OS X (10.6.8), & Server, PPC, & AppleTalk Printers