Those on Windows who want an open source IRC client should check out Xchat 2
http://www.silverex.org/download/ http://www.silverex.org/faq/I've been using xchat for a while, but while the code is free, the binary dies in 30 days if you don't register it.
xchat 2 doesn't have any of these limitations and has some more nice features, like a little tiny popup window in your start tray when someone addresses you in the channel.
