Why I Stand While I Work and Sit on Breaks
uxmovement.com
uxmovement.com
NYTimes ran a few articles a while back about this very subject..
http://opinionator.blogs.nytimes.com/2010/02/23/stand-up-whi...
http://well.blogs.nytimes.com/2010/07/14/phys-ed-the-men-who...
A key point: "The men worked out, then sat in cars and in front of televisions for hours, and their risk of heart disease soared, despite the exercise. Their workouts did not counteract the ill effects of sitting."