First off, what distro are you using? Do you already have Linux installed? If so, is your ethernet card working? You can do a ifconfig at the command line to determine this. The easiest way to setup the @home service is to use Linuxconf in X windows.
Let me know and I can help you set it up, as I have @home cable modem as well and have all my machines setup using the Linksys cable/dsl router.