the Linux Operating System (aka Gnu Linux, aka Lin Ux). An Open Source variant of UNIX.
created by Linus Torvalds (with non-kernel bits by Richard Stallman and others)
may want to consider WebMin for adding a GUI to admin tasks
article on top Open Source packages for sysadmins to use: Cf Engine, Nagios, Grub (instead of Li Lo), LDAP.
Apr'2008 article on picking a distribution