PaulyChat 

Paulychat is a straight forward network chat program. No bloat, and not very intrusive on your screen. Perfect for business networks.

Also, it's free...  No 'try now', or 'evaluations'..  It's Free to use.  

If you intend to use it for a while or are installing it as a service to others, please contribute five bucks to it's development. 

Just click here to download, or here for the stealth version, then install it.... and chat.