Pandion is a free instant messaging application for Windows with which you can communicate with your contacts with their accounts supported by the Jabber protocol.
It has a lot of options like support for avatars, conversation history, personal messages, emoticons, plugins, file sending, blocking users or sound support.
You can also add contacts from other networks like Windows Live thanks to the adding Transports option. This way you'll have all your networks into one. All of this makes Pandion a great instant messaging utility that's worth the try!