Well TCP traffic is the primary form of connection used on the internet/IP ... the other big player is UDP... the biggest difference being is TCP extablishes a connection so there is true handshaking for data integrity where UDP is sent with no guarantee that the date arrived intact... I cannot imagine that you are not using TCP.... I haven't used WinMX recently... I may look into it's setup to see what I can find out there... I don't think that would be your problem though. IF I were you I would post this question in the Limewire / MAC section in hopes of snagging the attention of a knowledgable MAC user as this may very well be an issue regaring using a MAC.