Desperate need of an update!
I have a Dual 1.25 GHZ Power PC G4 2 MB L3 cache per processor with 2 GB DDR SDRAM. I need to update the OS. How high can I take it and do I need to go step by step up the OS food chain to achieve this? Got an iPhone 6 for Christmas and can't download anything on it.
Mac Pro, Mac OS X (10.5.8)