Workgroup not working

I have three machines (98/XP Home/XP Pro) on my LAN running as a workgroup and linked to the Internet via a router and cable modem.

The XP Pro and 98 machines can not view the workgroup (network not available error) at all but can ping the other machines fine and access the Internet.

The XP Home machine shows the other 2 computer under the workgroup but can only connect to the 98 machine shares. No shares show on the XP Pro machine.

All the network setting are default except computer name and workgroup which has been checked several times.

What did I overlook?

Thanks