I have two 19" 1440x900 LCDs, both landscape, and would like to add a third. Bigger monitors can be nice, but I'd rather have the physically segregated visual space. As to whether that third monitor would be landscape or portrait, I'm agnostic. But if I had a FOURTH, I'd probably put portraits on the left and right (browser, Outlook, and Acrobat/Word) and two landscapes in the center.