Not an answer to your question..... but you may be interested as a MSN Messenger user! There is a brilliant add-on for Messenger called Messenger Plus - I've been using it for over a year now, and the latest version is now out (beta).
It lets you log messages and events, assign different sounds to different users (when they log in), remove the MS adverts and loads more!
Have a look at
http://www.patchou.com/msgplus/
(but it has been down recently because loads of people are hitting the site - keep trying or search for Messenger Plus Forum and you can find a download mirror there)