It sounds like you are using netbeui, however in case you aren't try enabling netbeui on your internal network. Netbeui is an incredibly easy to configure network protocol for small microsoft networks. It generates a bit of active network traffic, but this should not be a problem on a small network. Also if you have an open internet connection that you are sharing make sure that your proxy/firewall does not pass the netbeui packets, nor allow them from outside, or you will open your network up to the world (remember the cable modem situation where everyone on a local hub could see everyone else?)

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Death is lighter than a feather - duty heavier than a mountian.