KDE is alot prettier and cleaner then Windows, as well as faster. If you're looking for a PC for gaming, Windows is the way to go, but if you want a general purpose computer, plenty of popular programs support Linux, as well as plenty of more obscure ones.
Linux is a lot more reliable then Windows, more secure, and easier to hack and customize Linux, and personally, looks a lot cleaner.
Best of all, it's free. I don't know why people hate Linux, unless you want to play video games Linux is IMO the best choice.
Heres a screenshot of KDE 4.2: http://www.kde.org/announcements/4.2/scr eenshots/desktop.png