Zing dont go for ICS thats the worst bloody nightmare you can configure
Rich take JonT's advice and return the modem and get a standard router.
you'll have the new unit installed within 5 mins if you just take the modem off the power otherwise connect main pc wired to the router, log into the router and set the connection type to Dynamic. there the only thing you need to do is clone the mac address of the pc, connect the router to the STB or Modem and bobs your uncle.