There are two adjustments in my IT setup that hugely increased my productivity: 1) move to a huge monitor, 2) add another monitor making a total of 3 screens: 2 big ones, 1 small one.
In this article, it is argued that 2 screens actually reduce productivity. I agree if you use the second one to check on your email, facebook, and Twitter streams. If you use the second screen for a different version of your presentation with comments, or the directory with the images you are using, a multi screen set up is a life saver.
Employees in large companies find it difficult to be productive, and when you look at people sitting in large open plan offices staring at tiny lap top screens, you understand why.