Hi, I'm looking to buy a mac pro for the purpose of video editing with final cut pro and etc. What kinds of specs would be ideal? Do I want to get a 6 core 3.33 ghz intel xeon processor for instance or an ATI radeon 5870? Most importantly, what kind of performance increases would I see in more expensive hardware? My budget is pretty high but i'm trying to keep it less than $4500. Thanks!