mIRC 4.7. Internet Relay Chat program. The various parts of this client have been designed with the aim of simplifying and speeding an IRC session. mIRC offers an IRC client combining the user friendly window's interface with the colors of Macintosh clients and the best parts of the power of UNIX clients. mIRC is designed to offer the new user easy access to IRC and the experienced user enough power to play with.

For more info, check out the mIRC homepage.
Or download mIRC here.