jIRC is a IRC client for the windows operating system. It's a continuation of an existing open-source client called BoxedIrc. I've forked the last release v0.3 into jIRC, and have begun adding new features and fixing bugs. I've requested a project on SourceForge.net, so hopefully I'll get that soon and can make a release, until then here is some screen-shots of jIRC in action.
The place I was hosting the screen-shots has disapeared, you can see them at http://sourceforge.net/projects/jircwin/.