http://blogs.msdn.com/jensenh/archive/2006/08/22/711808.aspx
Fitts’s Law, usability, and making Office 2007 easier to use with a mouse. (Interesting side point about how an application like Office can be made easier to use when maximised (because target areas can be made in effect infinitely wide or high); web applications can’t ever take advantage of this since they run inside a browser, and so don’t know where the edge of the screen is.)