One last piece of information from Motorola:
"Thank you for your inquiry
It is possible to connect two computers to the SB4100 using both the USB and Ethernet connection however Motorola does not recommend or support it.
We support the connection from the SB4100 to *one* computer only using
either the USB or Ethernet interface.
The Motorola Cable Modem Team"
I am aware that Charter Cable, in order to conserve bandwidth, will not hook up more than one computer per household in this area, and probably has a deal with Motorola, since they supply the modems, not to assist customers in making the two computer hookup using USB and Ethernet together. They know obviously that most people hook up multiple computers anyway using an Ethernet hub. Would the USB/Ethernet setup use more bandwidth?