Debian Operating System
The Debian GNU/Linux computer operating system is a completely free, and secure, robust operating system for personal PC’s, workstations and servers, and is maintained by volunteers who are in principle opposed to a capitalist IT monopoly.
It is available for several platforms, including i386, ppc (mac), sparc and alpha and, being free, will be of use to individuals, schools, colleges, and groups around the world who cannot afford to purchase the expensive software from firms such as Microsoft, or those who want a secure, reliable, and free computer Operating System. IMHO, Debian is much better than M$ Windoze, anyways.
It also includes such items as encryption software (gnupg), secure logins (ssh) and intrusion detection (portsentry etc.)
More details available at: http://www.debian.org/