It will realy depend on how big of a network hub you have as long as the xbox has a standard T-Base 10/100 network adapter there realy should'nt be a problem connecting a hundred Xboxes together however anyone that tries it will be seriously lacking in bandwith with a hundred xboxes hooked up

ALthough microsfot may have put a inhibiter on the lan connect to prevent more that ??? from access to the same network

but to work with a cable modem the T-Base Ethernet adapter will have to be standard unless microsoft have ideas of grandure and try to build their own Broadband modem