Want to get into a security career but have no experience hacking into systems?  Head on over to De-ICE.net and download the penetration testing livecds.  They are preconfigured environments that you'll fire up on a machine in your network (has to be a 192.168.1.0 subnet) and attack with your favorite penetration testing tools (Backtrack 2 Final is recommended).  I just finished the first disk and I gotta say, while its a bit simple, its pretty fun.  Its also a great starting point for anyone who has no experience penetrating linux systems.

There are two cds for level one and one cd so far for level 2, its still under development.  You will need a fairly advanced understanding of linux commands and tools to successfully complete any of these disks, but there is good help on the De-ICE forums.  These disks are great fun and very educational if you're interested in Linux security.