Chat Patrol is secure chat software.But this’s not freeware.
ChatPatrol Secure Messenger is a communication stack plugin that provides encryption services for Instant Messaging applications.
ChatPatrol Secure Messenger is a communication stack plugin which will provide encrypting features for Instant Messaging applications.

We tried this and saw better.

Some features of ChatPatrol:
· Support for AOL, ICQ, MSN, GoogleTalk and Yahoo instant messaging networks. Learn More
· New Beta level support for ICQ messaging
· New Buffer-overflow protection – protect your computer from malicious exploits!
· New support for GoogleTalk (support only for official GoogleTalk clients, no third party client support)
· Does not require the modification of proxy ports or the starting of additional applications to enable security
· 1024 bit Diffie-Hellman Key Agreement for each secure session
· Automatic detection of other ChatPatrol users. ChatPatrol can determine that another user is using ChatPatrol and prompt you to configure them for secure communications
· 256-bit AES encrypted conversations
· Solutions like Trillian encryption and GAIM plugins require that the same IM client be used on both ends. With ChatPatrol installed, you and your chat partner can use different clients (GAIM AOL, Trillian AOL, GAIM MSN, etc)
· Can ensure that links that are passed in messages cannot be clicked on. This helps prevent Instant Messaging borne worms and trojans
· Automatic product upgrades. As new versions are made available you will always be up to date!

Requirements:
· Windows 2000/Windows XP
· Pentium class (500 MHz recommended)
· 10 MB
· Broadband or Dialup Internet connection

Developer company is:ELMTree Software
Software size is: 3.4 MB
You can use it with: Windows 2K / XP