I have a 2008 Mac Pro and after installing Civ 5, I've started to realize how outdated my graphics card is, even though I upgraded from the basic one at the time. I was looking on Apple's site and see that they offer the ATI Radeon HD 5870 card for $450, or $405 for education. But Amazon and NewEgg are selling it for $300. Folks on Apple's site say that it will work in the 2008 MP even though Apple says it's only supported in 2009 and 2010 models. The question is: Can I buy it from Amazon for 2/3 the price, or do I need to buy it from Apple? Like, does Apple have some sort of proprietary firmware on theirs or something that would prevent a "generic" one from working in the MacPros?