Interesting article from the real world. From this article - real world accounts - yep, generally Macs definitely cheaper and less stressful - unless you've got to have virtualization for Windows.
http://www.macworld.co.uk/mac/news/index.cfm?RSS&NewsID=3217406
http://www.macworld.co.uk/mac/news/index.cfm?RSS&NewsID=3217406