I have tried, not to use MSN for a long time, however now I have failed. At my new job most of the communication between people working at an other location (think a customer location) is done by MSN. At my previous job we used a IBM corporate tool but due to the fact that my new company is not big enough to run there own chat server only for those cases that someone is at a remote location we use MSN. Meaning, I have to use MSN. My big problem was that it is a Microsoft service and I did not like to use it. Why not use IRC relay chat instead of something like MSN? Now more and more people are using it and because of this I have started to use it.
Because I wanted to run it on my Mac I needed a Mac client for MSN. I have tried several MSN clients for the Mac and finally found the Mercury Messenger V1.8 the best suitable for my needs. Mercury Messenger was formally known as dMSN. Mercury is a java based MSN client and it works like a charm, in my opinion. I just installed aMSN on my girlfriends Linux laptop so, including the others I tested and discarded, I have tested several non Microsoft MSN clients and I have to say they all work better than the client presented by Microsoft.
So if you need to use MSN, download a non windows client and start having fun.