I have received a Mac Pro 5.1 with dual Xeon e5620, 24gb of ram, 1tb drive, and an ATI card that is not so great. I have been trying for days now to get OS X to reinstall. I have a copy of Snow Leopard 10.6.3 and no matter what I do, I can't get the system to boot from it. I got a copy of 10.7 and tried that and it still doesn't work. I came across something that said the OS was tweaked to work on that system and that I would have to get the original install discs that came with it when it was new. As far as I know, I will not be able to do that from the person that gave it to me because I am sure they don't have it. How else can I get OS X reinstalled on this system?