The writing has been on the wall for a while now, that the close relationship between Microsoft and Intel (and by extension AMD) is crumbling into dust. In fact, they have never really been the best of friends. It has been clear since Microsoft unveiled that Windows 8 would run natively on ARM processors that things would never be quite the same again. Apart from some niche server variants of Windows, which could run on Itanium and other processors, all the previous desktop versions, including Windows 7, have run on x86 (and x64 for the last 6 years or so) processors.
However, Microsoft is keen to increase its presence in the lucrative smartphone and tablet market, where it's not had much success so far, getting comprehensively trounced by Android and Apple. Microsoft would be happy to use an x86/x64 processor for this application, but here, the limiting factor is the energy source, the battery, forcing the entire device to consume very little power if it's to run for more than 5 minutes. To meet this requirement, processors based on the ARM architecture have met this need admirably for years, with excellent performance while the Intel x86 variants have not (see video below). This has lead Microsoft to forge a relationship with a new processor manufacturer, Qualcomm, who make their own variant of the ARM processor, called Snapdragon. In fact, the relationship is so close now, that Windows Phone 7 only runs on Qualcomm ARM chips.