Although IBM may have committed the original sin that allowed Microsoft to dominate the desktop, it couldn't have stayed on top for so long without Intel. Windows is so tied to Intel's CPU that the industry came up with "Wintel" to describe the symbiotic pairing. But now, Intel is becoming a player in Microsoft's undoing.As the PC market has changed over the past quarter-century, Intel has delivered CPUs that can run Windows for that market in the way in which it is accustomed. There have been some close calls, for sure; Intel was slow to react when low-end PCs became popular and AMD swooped in to grab that territory. But Intel is as cutthroat as they come, twisting arms in questionably legal ways to win back customers.

The move towards mobile computing has been a tougher challenge. Although Intel makes their low-power Atom chips for portables and netbooks, the tablet and cell phone market is dominated by ARM. The challenges of taking a complex desktop/server architecture like x86 and shoehorning it into a low-power CPU at a competitive price may just be too great, judging by the reaction of mobile hardware makers. And unlike the desktop situation, hardware makers aren't forced to use x86 because it's all that Windows can run.

That freedom to pick something other than Intel must feel great for tablet makers, but it has to terrify Microsoft. Only x86 can support the real desktop Windows operating system. If Wintel has no hope of making it to an ultra-mobile platform, Microsoft loses all the influence that its installed base carries. Windows Phone may share the same word, but it's not the same platform and doesn't have the same sway. As more mobile hardware runs Android or iOS, the Wintel duopoly begins to melt away.