The problem I have with that chart and the article - Vista was unpopular and didn't deliver on a lot of it was supposed to. So, people stayed on XP. When Win7

The problem I have with that chart and the article - Vista was unpopular and didn't deliver on a lot of it was supposed to. So, people stayed on XP. When Win7 came out, it was a solid rev from both XP and Vista. Thus, the strong uptake in upgrading. With Win8 - you have an install base that is already fairly content with Win7, a new interface that gets mixed reviews in the trade press -- yet people who use it find things they both like and dislike, and as others have stated computers have been "good enough" for awhile. I'm not sure if/how Win8 will play out, but corporate upgrade cycles and OEMs will play heavily into that. That said, a number of formerly PC only corporate environments are becoming more Apple friendly, which will also have an impact.