Linux

Fedora Project - http://fedoraproject.org

Mandriva - http://www.mandriva.com

OpenSUSE - http://www.opensuse.org

Ubuntu - http://www.ubuntu.com

Gnome desktop - http://www.gnome.org

KDE desktop - http://kde.org

Kubuntu (Ubuntu with KDE desktop) - http://www.kubuntu.org

Linux Mint (Based on Ubuntu with extra media capabilities) - http://www.linuxmint.com