If you're going to consider renderring, correct me if i'm wrong but the more cores you have the better it will satisfy your needs. If I were you i'd get a dual socket motherboard and have two of those Phenoms, also maximize your RAM. Dual socket motherboards can support as much 64 Gigs of ram, depending on the vendor. Also a thing you have to take in account is your GPU, all of your renderring will be done mostly through your GPU, you either want a Nvidia Quadro series or TESLA, or AMD's FirePro series, these graphics cards provide the best when renderring. Best of luck to you
Actually the graphics card is only important for rendering the image in the viewports, the final rendering (and the most resource and time demanding one) is done on the CPU. Since he's an architect student, any professional graphics card would be overkill because he won't be modeling/rendering organic objects which are the most demanding models for the graphic card.
As for the processor get the AMD because it has six cores. Or, as deadjon suggested, get the six core i7.
If you are working with a limited budget, then you can save yourself some cash and go for the X6 1055T.. As for the graphics part, Horhe as explained it correctly.. Unless you are working with huge texture data and high polymer count, a professional video card solution will be unnecessary..