Hello, Im looking at getting a used mac pro, and i was looking at getting it off macofalltrades, or if u know a better site to get it from i would like to know what u think. but im not sure what is the oldest i can go before not being able to put the newest os x on it. i see things from 06 and just think that it will not be able to run any of the new os. i plan to upgrade the ram, and gpu. but not cpu. im looking at doing some gaming on it like sim city, and star craft 2. but this will be my first mac im done with allways using windows. thanks for the help! Volker!