XChat is an IRC chat program for Windows. It allows you to join multiple IRC channels (chat rooms) at the same time, talk publicly, private one-on-one conversations etc. Even file transfers are possible. It has a choice of a tabbed document interface or tree interface, support for multiple servers and is highly configurable. Both command line and graphical versions are available.
[advt]XChat is a full-featured IRC client and includes all basic functionalities that are found in most other IRC clients, including CTCP, DCC file transfers and chats, and a plugin system for various languages. By writing plugins, one can extend the features and customize the functionality of XChat.