Though they don't really consider themselves a desktop environment anymore, as they renamed "KDE" to "KDE SC", for software compilation (which, in my opinion, makes a bit more sense since KDE is just as well about the many programs surrounding it than only the Plasma Desktop and kwin Windowmanager).
As for trying it out in Windows, give this a spin:
http://windows.kde.org/Last time I tried it, the Windows version was far from stable, though. So if you want the "full experience", you should consider switching to Linux.