If all the computers have shares setup, and all have tcp/ip and netbeui, then they should be able to see each other. If they all have ip addresses 192.168.0.x / subnet 255.255.255.0.... the only other think to check is that they all have the exact same workgroup or domain name (including capitalization)
Make sure all link lights on the hub are lit. You should not be using the "uplink" port on the hub -- just the numbered ports.
If none of your computers are a "server", then you will need the NetBEUI protocol installed on all.
See if you can ping between all the computers. Report more details back to us if the problem persists.
You might have to go into the network card on the computers that absolutely will not work, and manually lock down the media type to 10BaseT, full or half duplex. Some nics operate better when not on auto-sense.
Good Luck.