[Suicide Junkie]

A router would be simplest.
Just plug the cable modem in, and run cables between everything.
Power on in order from modem to router to computers, and it will just work.

If the old PC dosen't go Online very often, you could call up tech support, have them clear your ARP, and then plug the old PC into the modem.
Then switch back, calling tech support again.

You could pay $5 or $10 a month for a second IP address.

You could get a second network card, and do some internet sharing from either PC to the other.

If you were on DSL, Sympatico gives you two IPs by default, but add any more and you'll need one of the above steps.

A router will be your best (simple, added security, long-term) solution, if you have some cash around. They're not too expensive anymore. Built in firewall, NAT, and if you ever fill the router, you can add the hub to split off to more computers.
With a wireless router, you'll probably not get as many ethernet ports, but it'll be enough for your setup, and you can always add the hub downstream of the router to get more.

Cheapest would be to call tech support and get them to clear the settings each time you want to switch computers.
After a few times, they'll know you, and it'll take under 30 seconds once they answer the phone.

[ September 16, 2003, 12:39: Message edited by: Suicide Junkie ]