Audio and Video - dynamic ports were chosen for the audio-video (AV) stream.... using dynamically allocated UDP ports in the range of 5004 to 65535.
Application Sharing and Whiteboard - whiteboard (WB) data uses port 1503...
File Transfer - Both incoming and outgoing TCP connections use the range of ports from 6891 to 6900...
Remote Assistance - TCP port 3389 is used for the TCP connection for the Remote Assistance protocol.

The MSN Messenger port numbers below are taken from (amongst others) PortForward.com and Experts Exchange discussions Q20968914 and Q20660861.

Unfortunately, trying to block MSN Messenger ports doesn't work because of the wide range of ports including port 80 that MSN Messenger uses:

TCP port 80 (the 'http' standard web port - see also Web Messenger blocking)
TCP port 1863
TCP port 6901 (possibly)
TCP ports 6891 to 6900.
UDP on ports 1503, 3389, 5004-65535