BackTrack 5 GNOME-64 ~ 1.87 GB

The evolution of BackTrack spans many years of development, penetration tests, and unprecedented help from the security community. BackTrack originally started with earlier versions of live Linux distributions called Whoppix, IWHAX, and Auditor. When BackTrack was developed, it was designed to be an all in one live cd used on security audits and was specifically crafted to not leave any remnants of itself on the laptop. It has since expanded to being the most widely adopted penetration testing framework in existence and is used by the security community all over the world.
BackTrack Clean Hard Drive Install