For MSN chat try Jabberwocky. Jabberwocky is an implementation of the Jabber client which also has 'transports' to chat with MSN, AIM, YIM, and ICQ users (provided you have an account with the respective chat protocol).
It's slightly rough to get set up with Jabberwocky, but once you've configured it properly it's nice to have simply one chat program for all the different transports.
