NVIDIA 8800 dosn't work - ATI 4870 does !!!
Even the NVIDIA support couldn't bring the NVIDIA 8800 GT (1st Generation) Graphics Upgrade Kit for Mac Pro running in my MacPro 1.1.
So I decided to order an Apple Graphis Card Upgrade ATI 4870 which should official not work in a MacPro 1. Gen. But it does without any problems. Today I installed the ATI 4870, startet the MacPro 1.1. and it works. In addition I have a mini display port for the future.
So forget NVIDIA 8800 - spend more money and buy a ATI 4870 !!
Kind regards
Friedrich Guenter