ReactOS : Is technically not a linux distro, and in fact it is not a distro at all. What?!?!?! Well it is a project of building windows from the ground up again and it is free and in alpha but it is so freaking sweet that they are doing this. Basically reverse engineering Microsoft Windows and building it up again and this time it is free. Yes, Windows for free, it is possible.
Grab the ISO here:
Extra, extra read all about it; Free Windows!