I'm looking into getting either a MacBook Pro 13" or 15" in a few months for use as my main computer. I will be using a lot of architecture programs like Revit and AutoCAD (I really wish these ran natively on OS X) and need to know if the 13" screen is plenty big or if I should get the 15" screen. Portability isn't a huge issue so I'm not concerned with weight. Also, what processor speed should I get so that I can run these programs smoothly? Thanks