ReactOS
Jason Filby's
ReactOS project, aiming to produce a free Windows NT 4.0 clone distributed under the GPL license. The developers of this
OS keep a low profile, however they are making big strides. ReactOS is now able to boot and start simple win32 console-based applications. Best luck to them for the rest of the immense work. As of this update (02/08/03), ReactOS 0.1.0 supports CD booting and self-hosting. Doing well so far, but they'd better hurry up and implement that DOS subsystem!