Reading this, it appears that they sold more Windows Mobile (6.x) devices than Windows Phone 7 devices. 3.6M total sold in Q1, 1.6M of which was WP7.
This shows actually that people buys the unit and not the Operating System. They'll walk to a shop, try a HTC phone, like it and buy it.
Re: Microsoft sells 1.6 million Windows Phone 7 devices in Q1
#21I think some buy the unit after playing with a number of them, some buy brands, some buy the platform/OS (which overlaps brand for half the market) and some just buy whatever the salesguy pushes on them.