If you have a firewall, just block the relevant ports (135, 137-139 and 445). Blocking NetBIOS is a very good idea anyway if you're connected to the net. On NT/W2K/XP you can also disable the messenger service (I don't know if or how it can be done on 9x).
It's not about MSN Messenger, but Windows Messaging which is a way to send messages to machines on your LAN. The intended use is for Administrators to broadcast important info (e.g., server downtime) but, in this case, it has been exploited/hijacked by spammers.
are you talking about those messenger popups that come up on your desktop... when u leave your comp on I come back the next morning to find like "XXX teen" or "Message from: blah blah... Try new products and stuff"... That stuff? This gets rid of it this link? I got it through emails WMKLEz virus or so i think.
besides the standard porn, money grants, merchant account spam i get - i sometimes get buisness spam -- every now and then i get a "get by those pop up blocker programs" buisness count on blah blah blah blah -
with the increasing amount of people using those progies i think that either free services will stop or use a detection scheme and send you warnings (which i doubt) or they will just figure out to get by them (using the things i get spamed with (if they are for real) or come up with ones themselves