Hacking MSN is actually VERY simple. Msn is designed to route the connection through a microsoft server while you are chatting. However, when a file is sent, a DCC (direct connection) is created. This was purposely done because otherwise microsoft would waste alot of bandwidth so a direct connection is made. This is your chance. Make a file transfer occur between u and a victim (try to send a big file), open up your command prompt (run "cmd" in NT/XP or "command" in 9X to get into prompt) and run netstat. usually the MSN targets IP would be above port 2000. enjoy.
If u recieve some crap like gux1-43.primus.com as the target, do a reverse DNS lookup on it. However, this occurs very rarely, mostly u will recieve a clear IP.
once u have d IP u can do anything with him by Fingerprinting.
U can protect yourself from this occurring to you by using a proxy with MSN (under connections panel in options).