SCIM, or Secure Cryptographic Instant Messaging, is the answer to all your concerns regarding your electronic privacy. This software encrypts your messages using the latest in encryption technology before they leave your computer and doesn't allow any decryption of messages until they arrive at your colleague's computer. In essences, this is the best secure chat software on the market today - and it's free for non-commercial use.

http://www.projectscim.com/