Just wanted to update everyone on this. So I suspected after talking to all of you and performing some other test, that it was indeed my graphics card. Well, today I went to the Apple Store and purchased a new ATI Radeon 5770 graphics card for my Mac pro and the Mac Pro boots perfectly. So it was indeed just the graphics card and not the logic board or CPU's like Apple told me. Oh and one other thing. I have a Mid 2006 1st Generation Intel Mac Pro and the card works perfectly. So to all who helped me, Thank you very much. I owe you all a beer..