I see a few problems for windows in the IoT realm:
1) Its to heavy. Even the embedded versions need a decent CPU and memory to chug along. Try running Windows on the RPi hardware.
2) Its to heavy. ARM is powering/going to power the IoT since it is so good for lightweight systems and low power usage. Yes, there is Intel Atom, but that series of chips barely makes a dent in the world of connected things.
3) Linux already powers this entire market and development for Linux is cheaper (no Visual Studio licenses) and easier (huge open-source and developer network).
4) Its Windows. Great for businesses, not so good for small, tiny, low power devices.
