XPde

It's a desktop environment(XPde) and a window manager(XPwm) for
Linux. It tries to recreate the Windows XP interface to-the-pixel
point. Nothing more, no clipboard compatibility between Gtk and Qt
applications, no emulation of Windows applications, no unification on
the widgets of X applications, just a desktop environment and a window
manager.

http://www.xpde.com/
http://slashdot.jp/articles/03/03/16/2335210.shtml?topic=84