I recently read a blurp by Dvorak in PC Magazine mentioning an open source version of Windows XP called ReactOS. According to the website (www.reactos.org), “ReactOS® is an advanced free open source operating system providing a ground-up implementation of a Microsoft Windows® XP compatible operating system. ReactOS aims to achieve complete binary compatibility with both applications and device drivers meant for NT and XP operating systems, by using a similar architecture and providing a complete and equivalent public interface.”
The website provides much more information including screen shots of React running Windows apps and games and downloadable copies of the OS. The current version of the OS as of this writing is 0.3.4 and is still in alpha. There was an iso image of an install CD for the OS as well as a VMware virtual machine. I downloaded both, but fired up the virtual machine for a quick look at React. The VM only allocates 128MB of RAM and a 2GB hard drive, but the OS booted up very quickly. It is not feature complete, although it had a Start button, system tray with clock, basic Control Panel, and My Computer, etc icons on the desktop. This is definitely alpha as there were very few programs with the OS, the explorer app would leave grey shadows of closed windows behind and acted quirky. But I do see great potential for this project and hope the developers can reach there goal of a fully-functional OS. React is definitely worth checking out.