I've also assessed things Apple/MS in a post of my own. I don't think it's become public realization yet, but Microsoft is scared. Apple poses a serious threat, and they have recent experience in starting the long and dreadful decline in the browser space to help them get a taste of the backlash that's coming.
http://blog.iamron.com/business/microsoft-buys-customers-cow...
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Microsoft's Revenue Drop
* PC buyers care about their computers less than Apple buyers, so in a global economic downturn, they cut back on new computer purchases moreso than Apple buyers
* PC buyers are waiting on Windows 7 (mentioned in passing by Gruber)
* PC buyers feel higher levels of satisfaction with their computers than in previous years, and feel an unusually low need to upgrade
* PC buyers have consolidated their personal inventory, perhaps owning only a single laptop (maybe work issued) as opposed to a laptop and a desktop
* Microsoft is not attracting first-time computer buyers as much as in previous years
* PC buyers are switching to Apple
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Apple's Growth in >$1,000 Sales
* There are fewer PC competitors in the market
* PC buyers feel that equal or greater value is achieved in the <$1,000 market
* The >$1,000 market has contracted around Apple
* Apple is attracting more first time computer buyers than in previous years
* PC buyers are switching to Apple
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I don't know how probably true these explanations are, before or after reading Gruber's article.