I used pidgin at first before we could integrate msn and others in to converations, but now I have everything integrated and I love how easy they are to use. You can link all account to your friends, as all the contacts from different services are collected in to your contactbook, and as the contacts has a merging tool, it's very easy to merge contacts(as to not have doubles if you have a same friend on msn, facebook and gtalk for example.

I use pidgin for IRC though, which works very well.