How can i hook My Ibook G3 up to my Telewest Connection?

Hi There,

I have a Dell PC in the dining room that my children use for internet etc etc, but have recently purchased an Ibook G3 and would like too hook it up to a telewest cable modem, it is feeding the pc via USB and there is a spare Erthenet port, can i some how connect the ibook via the erthenet port, dosent really matter if they dont both have internet at the same time, i really want to download some updates for the ibook.

Thanks