I have a Dell that I am trying to hook up to the network but it's not wanting to work. I swapped cables. I checked to see if the NIC was good. I also plugged the CAT 5 into two different plugs, one of which I unhooked a working machine to make sure I had a good connection and none of them worked. When I plugged either cable in I got no lights on the mini-hub we have in our office. Could the problem be that they have a special kind of NIC that is used for telephone operators? This machine has always had a few problems getting onto the network so they kept it as a stand alone but now they have to have this on the network but I don't know if that is possible if their NIC that allows them to do their job is the problem. When I looked at the NIC the only writing I could see on it was bel 00S8 WM but I'm not sure of the brand because if I remember correctly they had said they were installed by a different company that they had to special order them from.
I personally am not aware of special telephone operator NIC's. Assuming you talk about a desktop, the Dell either has a built-in NIC or a PCI-card. If built-in, disable it and insert a PCI-NIC. If a card, replace it with another. Cards only cost about $15,-/£8.- Try to get the network going, before you try anything special with tel-op stuff. Perhaps the mini-hub has faulty contacts or is too slow. Why a hub and not a switch?
It does sound a bit like a HomePNA card. They use Ethernet 10 Mbps connection but through a phoneline. But before making false assumptions, have you checked what kind of drivers / utilities it has on computer? Those could say what kind of a card it is.