You make a good point about the customer satisfaction program.  I wonder how many people opt out of it fearing privacy concerns.

I got my 40% for XP here and here (the Wikipedia article lists both numbers): 

  1. http://en.wikipedia.org/wiki/Windows_XP
  2. http://thenextweb.com/microsoft/2012/12/01/the-big-fight-begins-windows-xp-drops-below-40-market-share-while-windows-8-passes-1/