Enjoy, That was NetBIOS name service, so not even intruding attemp, just ignore it... the story is MS was using all kinds of broadcast for windows users to get to internet or browse their neighbors. If you see port 138,139, those are sililiar services attaches to MS Windows too. But, starting from Win2000, they should fix it by using WINS as default, but NT4 needs to configure it that way i believe (by determine the node type)... I am not a MS guru, so please correct me if i was wrong...
J.C. : I think ZoneAlarm is a pretty good firewall application for windows users and free, but just keep in mind to update it to the lastest version to fix the security holes...BlackICE is popular too. If you are familar with router stuff, there should be tons of choices over there right? You are doing Natting, which is good when working with ACL's. If you can set up reflexive filter, then the router would be pretty much a firewall just acting as a PIX...