Why would you want to use KDE with Windows? Do you want something like: Talisman which is just a different set of eye-candy? Or do you want the entire environment? If the entire envi, then bear in mind that M$'s software do not easily allow replacement of its organs, unlike open source software. And as the other poster said, too many conflicts

IMO, there exists no advantage to using KDE on Windows to make the excessive trouble of porting the blue-side to the dark-side worthwhile...