New Router/Modem=Lost LAN

Hi,
recently I bought a new Billion BiPac 7202 4 port Router and modem
combined?? to use in place of an old SAR 715 4 port router/modem. With
the old SAR, each Win2K machine could see each other and shared folders.
With this router, an IP address was specified in TCP/IP properties as
was a gateway.
Now, with the new Billion router/modem, no IP is required as it is
detected automatically in TCP/IP properties, and so even tho' each
machine can see each other, there is no folders to see nor printing.
I have set the gateway as 192.168.1.254, as that of the Billion router,
but file sharing is still not possible.
Am I missing something?

Thanks
--
Bob H
Leeds UK