Alright so I know I won't be the first to purchase this card, but I am certain at this point I will. And I'd like to provide some evidence for future users.
Oh random here, but this cart helped me:
Mid 2006 - MacPro1,1
Early 2007 - MacPro2,1
Early 2008 - MacPro3,1
Early 2009 - MacPro4,1
Mid...