I do hope that you don't have File and Print Sharing enabled on the adapter that connects to the Internet or else the whole world can see into your network.
Using NetBEUI is a kludge that actually works quite well and can enhance security if you are using ICS, though purists frown on it I did use it briefly until I set up a FreeSCO router for my home network. I'm not sure why you can't see the other machines just using TCP/IP, but note that the M$ firewall (sic) can interfere with this.