At the last place I was working (as an employee) I had 4 displays. 17" laptop display 2 - 24" Dell monitors (I think 24") 1 - 19" LCD Frankly it was too much.

At the last place I was working (as an employee) I had 4 displays. 17" laptop display 2 - 24" Dell monitors (I think 24") 1 - 19" LCD Frankly it was too much. I mostly used the two 24"ers in the middle and used the outriggers for email and other junk like that. It actually did make it nice to have VS.NET, Flash, FlashDevelop and IE open full screen on a separate monitor, although I lost track of the mouse quite frequently. In your case, I'd recommend buying the biggest monitor, with the highest resolution you can afford. I'm with Rands on this that the most pixels win.