DaVince KDE 4 is mostly applications. QT framework is OS netural but is not OS neutral enough to hand Windows Manager porting. Past ports have been insanely slow. Ie X11 server on windows so the windows manager works. Basically X11 windows manager design and Windows windows Manager design are incompatible. Yet lot of things do perform way worse on windows. Ie that you can take something across to windows does not mean you should.
