True, but.....
Tacpot, you're absolutely right, the MS machines can and do use TCP/IP for self discovery (that's the whole point of SMB which is NetBIOS over TCP/IP).
In my experience of setting up LANs of varying sizes, a TCP/IP network will often appear (ie in Network Places) as incomplete or "unbrowsable". Addition of NetBEUI to at least one of the machines on a LAN has cured the problem on more than one occasion though!
Being a TCP/IP purist at heart, it pains me to add another ghastly MS protocol, but if it works then that's gotta be good news!
Try it - it may work!
Of course another reason could be that MERLIN on Master Green's network is not seeing MASTER as a gateway for anything other than the Internet (meaning that "browse lists" are not being updated on the client computers).
Can we get some info on what's in your network settings box?
Let's wait and see if Master Green has had any luck yet with all the suggestions thus far - let us know, MG!