Marcos Guglielmetti has announced the fifth test release of Musix, a 100% free multimedia operating system intended for music production, graphic design, audio and video edition, and all kind of tasks.
From the Musix Wiki:
It is a Free Operating system intended for musicians and users in general. It also contains an enormous collection of free programs. The system will boot from your CD/DVD drive, with no need to install anything on your hard disk. The programs currently support the Spanish and English languages.
Musix comes with Ardour, Rosegarden, DSSI synths, SoundFonts and lots more.
Visit the Musix website for more information and links to download Musix.