Despite comments I have seen, I believe 10 Base 2 (Coax) is more convenient for small networks. But then someone will along with a Laptop with only have a 10 Base T (RJ45) port. It can be connected to the Coax network using a hub (more untidy power cables etc). But, in principle, if an NIC in one of the networked PCs has both a Coax and RJ45 port and if the signals on one port concurrently appear on the other (logically connected), then the NIC is a single port hub and so the laptop can be connected to the NIC RJ45 on that PC using a crossover cable. But, is there any NIC where the Coax and RJ45 ports are logically connected? I cannot think of a reason why NICs cannot be this way.

there is no such NIC.You can use only one of them.All you can do is to get an adapter form BNC to RJ45 or a HUB with RJ45 ports and a BNC port.Connect hub's BNC to your Coax loop and laptop into hub's RJ45 port.

Damien, there are a lot of reasons why they can't be configured this way...think about it. You're not thinking straight if you think coax is easier, or better, than 10baseT. Aside from durability (coax tends to break down very easily if bent, or kicked or tripped on whereas Cat5 lasts a lot better and stands up to wear and tear better) You can't get the same speed from 10base2 that you can from 10baseT, but hey, if you like slow networks who am I to complain!

In the old days when hubs cost a lot then BNC was quick and cheap and pretty reliable. The main problem was if there is 1 faulty bit of cable or connection then the whole network was stuffed. Nowadays, if you have 2 PC's then a crossover cable will give you a 100baseT network no problem.