FOR HACKERS BACKTRACK5 IS THE BEST OS

Some of the Features of BackTrack 5 is, It is freely distributed to all, It contains many useful security testing tools, Fully Patched with all new and updated tools, Can be used without installing, Superb Look, Can be boot from a USB drive and Many more.....
Well Known Tools In BackTrack.....



Metasploit integration

1. RFMON Injection capable wireless drivers
2. Kismet
3. Nmap
4. Ophcrack
5. Ettercap
6. Wireshark (formerly known as Ethereal)
7. BeEF (Browser Exploitation Framework)
8. Hydra
9. Cisco OCS Mass Scanner A very reliable and fast scanner for Cisco routers with telnet/enable default password.

A large collection of exploits as well as more commonplace software such as browsers.
Tools in BackTrack are arranged in the following categories:

• Information Gathering
• Network Mapping
• Vulnerability Identification
• Web Application Analysis
• Radio Network Analysis (802.11, Bluetooth, RFID)
• Penetration (Exploit & Social Engineering Toolkit)
• Privilege Escalation
• Maintaining Access
• Digital Forensics
• Reverse Engineering
• Voice Over IP

Source: http://www.backtrack-linux.org/

 BackTrack is a Linux-based penetration testing arsenal that aids security
 professionals in the ability to perform assessments in a purely native
environment dedicated to hacking. BackTrack provides users with the largest
and the greatest collection of security testing tools.