Wow! This is a "rah, rah, gooo Mac" article. I'm not sure how accurate the claims for savings are, but I do know the author is barking up the right tree. Windows has gotten too expensive and that is pushing folks to look for alternatives like never before. Not just the Mac, but all sorts of things from Linux and thin clients to Macs to multi-user machines.
So, this is interesting and the general thrust of the article is clearly right. It's just the numbers that might vary, a lot.