It's surprising how much they've managed to port and get working at all in Windows considering its not a Unix like system. The great thing it uses Qt has the graphics library, which is very portable. KDE does however have a few external dependencies which is the main challenge.
Well, I'm not sure about that. If M$ has its ideas, they might require people to pay money for SUSE. Maybe more than a $100. Then they threat the creators and users of all other Linux distro's to sue them if they're using/creating new linux distro's that aren't from M$.