Pidgin is one of the most powerful universal chat clients which supports over 15 chat networks including MSN, Yahoo!, GTalk & AIM. One of the reasons why I think its extremely powerful is because of it’s support for Windows, Linux/UNIX, Ubuntu & Mac OS X. Another cool feature that Pidgin provides is that it lets you know about all your friends who are appearing offline :D. So, it won’t let your friends hide from you.
Complete list of Pidgin supported chat networks:
- Google Talk
If you are looking for a messenger for MSN support only, you should try Kmess which is easier to use and looks more like Windows Live Messenger.