Broken Glass is a set of open source apps, along with some fancy scripts that let you build a Live CD version of Windows 7.
Broken Glas Uses Windows AIK, the only Legal way to make a Live CD version of Windows 7, even if you don't own it! How, you may ask?
Well, Aik was made for programers who needed to test if there apps would work on Win7, and for making customizable Win7 installs.
So basicly AIK is the "bare bones" of Windows 7. It has no "Windows Explorer" or startmenu, so windows gives it away for free!
But.. with a few open source apps, we can replace what Microsoft removed, insted of Internet Explorer, we can have Firefox, and who needs Windows Media Palyer, when VLC supports like 8x more video formats.