So I picked up a 2006 Mac Pro (dual 2.66ghz) cheaply off of Craigslist (and I mean cheaapppp). I'm going to throw some used RAM off of Ebay in it and upgrade the processors to X5355's. Question I have is that eventually I will add a 6870 to it (and leave the 7300GT in it as my boot card), but will an AMD/ATI Radeon HD 2400 Pro work in my Mac Pro? I have one in a box from my old PC days and thought it might suffice for awhile (I have 3 monitors I would like to run). Any help would be greatly appreciated (and yes I know I could try it, but hoping someone's tried it before....).