You can setup a jabber aco**** with any server that supports it... and they interconnect... if you have a gmail account you can use gtalk instead... it's also jabber under the hood.

To get MSN support working through jabber look up: howto setup MSN transport in jabber. And I think you'll need to us a more advanced client on your desktop... like psi or gajim to find it, configure it and register it.

http://www.youtube.com/watch?v=4QouuPHWqBg

Hope it helps.