LAN File Sharing Problem

Im having some trouble with my file sharing capabilities over my LAN.
I have basically set up 3 computers in my house using a simple router to link them together, all 3 operating systems are running the exact same, fully updated version of windows 2000 pro. My computer connects to the internet, and the other 2 computers connect through my computer, this works perfectly.

However i cannot get the file sharing to work, i have configured all 3 computers to be the member of the same Workgroup and then ran the Network Configuration Utitility, and I have setup shared files on all 3 computers. However when i go into Network Explorer and click on the Computers Near Me, I am told i cannot connect to the workgroup, and when i type "\\computer name\" into windows explorer or a browser it still cannot connect to the other computers.

I have configured my firewall (Sygate Personal Firewall Pro) for file sharing, and the LAN Properties are configured for "Client for Microsoft Networks", "Virtual Machine Network Services", "File and Printer for Microsoft Networks" and "Internet Protocol (TCP/IP).

Like i said before, the Internet Connection Sharing is working fine and so it must be picking up the network, but i cannot get the damn file sharing to work.

Any help on this would be greatly appreciated.

Thanks in advance.

Daniel.