You can share the files through netbios broadcasts in two ways. The first way is as follows:
1) Use WINS/NETBIOS port 137/TCP and netbios datagram ports are 138 and 139 UDP.
2) Enable the NETBIOS over TCP/IP but not NETBIOS over DHCP
3) Use the IPv4 on both the system i.e. on Windows 2003 server and also on Vista. Because NETBIOS will not work with IPv6
4) Ensure that your NETBIOS bindings are correct to share between the sites.
Second way of sharing the files is through SMB shares over TCP. To do this, you need the followings:
1) An open path on SMB port 445/TCP, NETBIOS datagram port 139/UDP and RPC port 135/UDP.
2) Use the IPv4 not IPv6.
You have to do the above two ways simultaneously.