The Security-Onion is a live CD tool. As the site states:
The Security Onion LiveCD is based on Xubuntu 9.04 and contains Snort 126.96.36.199, Snort 3.0.0b3 (Beta), sguil, idswakeup, nmap, metasploit, scapy, hping, fragroute, fragrouter, netcat, paketto, tcpreplay, and many other security tools.Most (if not all) of the tools I have been posting on can be found compiled and ready on this distro.
The only fault I have with it is Xubuntu. I am not a fan. But this is just personal preference. I shall likely always remain a dinosaur who likes easier access to the text configurations over GUI based tools.
Best of all, there are a number of tools such as Cheops-ng that can be difficult to get running on newer versions of Linux (without adding a pile of outdated libraries).
The CD is a great way to get a set of tools up and running fast and effectively.
Good work Doug & Mubley.