What is BB4Win?
BB4Win (Blackbox for Windows) is an alternative shell for Microsoft Windows. The program aims to emulate the look and feel of a Linux based desktop. The BB4Win project was discontinued in 2005 but various branches have been built from the source. BB4Win's primary feature is speed. The interface is designed for minimalism to provide basic desktop functionality without wasting system resources on "bloated" or needless features. There are many plug-ins and hundreds of themes available to change the look of your desktop.
Latest release 2009, see http://bb4win.sourceforge.net/