I have the opposite affliction: I've become so used to my 12" Powerbook being able to hide under a legal pad (but not in a manilla envelope) that even the thought of a 13" Macbook is a little unpalatable.

On the other hand, I became wildly more productive when I replaced my old, cramped desk with a dinner table to spread all my crap across, so maybe the Pro isn't such a bad idea.