I've been using my laptop WUXGA+ (1920x1200) since I started, and I am finding that anything smaller simply shrinks the menus I'm used to seeing to something that takes more time and energy than a glance...
Two monitors is a really nice solution. With two you can have a 3d window open and your plans and editing open as well. Three monitors and you can have your editing and schedules and menus on the left, your plans in the middle, and your 3d and rendering on the right.
With the prices of monitors and gear shrinking all the time, one can get a very nice productive work rig...
HOWEVER
Getting work in the current economy will be the real challenge, eh?