KDE on Windows
Languages: عربي | Asturianu | Català | Česky | Kaszëbsczi | Dansk | Deutsch | English | Esperanto | Español | Eesti | فارسی | Suomi | Français | Galego | Italiano | 日本語 | 한국어 | Norwegian | Polski | Português Brasileiro | Română | Русский | Svenska | Slovenščina | српски | Türkçe | Tiếng Việt | Українська | 简体中文 | 繁體中文
Windows XP/Vista/7
"KDE 4 libraries and applications are available to you, no matter if you are a commercial developer, manager or free software hacker. You are invited to not only just use the toolkit - you can contribute your own solutions and improvements to the KDE community."
It is very helpful to be able to run KDE apps on windows without even installing anything.
http://windows.kde.org/
http://windows.kde.org/download.php

KDE on Windows is not yet in it's final stage.