MSN or Live Messenger is the best messenger out there. No rivalries. I can't find another one that even comes close. MSN does not normally get a lot of things right but they nailed it with msnm and the new live messenger shows theya re still at top.
Plus when you have a bunch of people logging on to a system with old software when the server is optimized for the new software update it causes crashes because the programing codes conflict. Ask any coder.