My router blocks em.... Including ftp, webserver, pings, etc, unfortuneately even after I turn the dmz off.
So I dont have any problem with that.
But anyway, this one geeky bastard found out how to sell this spam technique to companies. I lost the link though.
It uses Windows Messenger service. To get rid of it, just get linux, or Lindows I hear is good for people who cant learn Linux.

Maybe tonight we'll fly so far away... We'll be lost before the dawn...