[smoore]

if the previous suggestion of rebooting the cable modem doesn't work it's because of a MAC address (hardware address issue) probably. Each node has it's own MAC and some cable companies restrict users to one machine per account. The way around this is to go get a linksys router and use the "clone MAC address" function... you usually don't have to type squat:

1: plug router into cable modem
2: plug computer into router, use web admin interface
3: "clone this MAC address button" -> clickie
4: make sure that inet now works
5: plug xbox into router
6: pwn n00bz