Laptop I’m using has a crappy 1280 x 800 screen. I use that as a second screen and my main screen is a slighty better, but not amazing 1440 x 900.
I’d say the best set up as asliding scale would be
Best – 2 huge high resolution screens
Next – 1 huge high resolution screen with laptop as aux second scrren
Next – 1 average screen and laptop as second screen
Last – Laptop screen only
What I can’t fathom is that even though everyone in my office has the option of a docking station + proper screen/keybord/mouse they still choose to sit working on only the laptop, sometimes a 13″ one. Madness.