>    Incidentally, RR will not give me another IP address.  I suspect 
> they are using port monitoring to identify my first 48 bit NIC 
> address and when they see packets with another NIC address, they 
> refuse the DHCP request and I can't direct connect another system to 
> my cable modem...

Some people have reported success using a hub or switch connected directly
to the modem, particularly if you call and ask.  I suspect that this policy
is over, since they are now starting to offer "home networking" for an
additional fee.  They'll even provide the hub, for the right price.  A NAT
router is a great way to handle it though.

I'm not sure what you're saying about connecting a different system to your
cable modem.  If you do that, you have to reset the modem, but it will allow
the different computer to connect.