NetBeui not working

I set up a file server on an XP machine and can share drives/folders no problem using TCP/IP protocol. However, I wanted to secure the sharing to the local LAN only, so I installed the NetBEUI protocol and bound it as the only protocol for sharing on the server, and both it and TCP/IP on one of my other rigs. As soon as I disable TCP/IP for sharing on the server I can't connect to it. I can ping it no problem.

Everything is going through a WRT54G under DHCP. The subnet masks and gateways are the same.

What am I doing wrong? Or, can somebody recommend an alternate method of securing my shared folders from the internet?

Since you're using a hardware firewall, you don't need to use NetBEUI to control access to the shares, your internal LAN is segregated from the Internet. As long as your not forwarding ports 137-139 to a machine with shares, or some other means of exposing those files, they are not accessible to the outside. If you were using ICS or a software firewall on a machine with shares, NetBEUI might be of some use, but it's been pretty much depreciated since Windows 2000 and has been mostly replaced with NetBIOS over TCP/IP.

Eewwwwwwwwwwww newbeui......so 1990's.....

Ditch NetBEUI. If you want to secure the file server from anything but the LAN just don't give it a default gateway.