I'm pretty set as far as PCs for work/gaming/etc. I have a Mini that I tinker around with, nothing major. I just quit WoW (/whew), so now gaming isn't that big of a deal. I was thinking about picking up a MB and maybe start doing more work on the road. My current PC laptop is pretty old and only get about 40 minutes of battery life, so for 'mobile' computing, it's pretty useless. I heard rumors of the MB's lasting 3-4 hours which sounded pretty slick.
Yes, it is too small.
I have used MBs extensively and I always find that the screen is too small for me. I am used to a 15.4 and I love the extra real estate that it provides. I will finally buy a MB of my own when they finally release one with a larger screen, I refuse to buy a MBP because I do not need that.
Out of curiosity, have you used a Macbook with Spaces? I honestly would rather take my Macbook with Spaces over my 30" ACD. Its like having my own 30" monitor in the size of a 13" laptop. With the way I have applications set up and my mouse configured (LG VX Nano mouse), I never have the feeling of running out of real estate.
I actually wish there was a 13" Macbook Pro. Once a powerful but extremely portable MBP comes out (15" is not extremely portable in my opinion), I will jump ship to that.