Originally Posted by PR_Phil

Studies show that adding a second monitor to a setup for a person who spends significant amounts of time analyzing data, editing files, cutting and pasting, doing comparative analysis and other tasks that are facilitated by the ability to view multiple files without having to click between windows, will increase that persons productivity by anywhere from 9% to 30%.

on the low end you are achieving a 9% gain in productivity, making adding a second monitor to most situations the cheapest, easiest and fastest way to increase productivity.