Although Microsoft recently touted having sold 100 million Windows 8 licenses this week, careful observers noted that selling all those licenses doesn’t mean vendors have actually sold 100 million Windows 8 devices over the past half-year. ComputerWorld this week talked with Patrick Moorhead, a principal analyst with Moor Insights & Strategy, who estimates that the actual number of Windows 8 devices being used out in the wild is closer to 59 million, since the most recent data from Net Applications shows that Windows 8 is being used on around 4.2% of all Windows PCs.

While 59 million sounds like a large base, keep in mind that there are still more than 70 million PCs out there using Vista, which might explain why Microsoft is more eager to talk about the licenses it has sold and not the number of computers using Windows 8. As Moorhead tells ComputerWorld, “No specific news from Microsoft [about the total install base] is bad news, because if it was good news, Microsoft would be shouting it at the top of their lungs.”