hi knowhal...
welcome to the forum
should be straighforward to get this working, turn off the pc/pc's , the modem and the router.may be worthwhile to remove the catv cable from the modem too..might not be neccesary, but from experience have found that by doing this the first time, it might save you repeating the procedure. once the catv has been out for 10 or so seconds, screw it back in and power up the modem, with all leads connected. wait for the sync and rdy to lock on, then power up the router, again with all leads connected, and again wait for any lights that should lock on, to stay on. finally boot up the pc/pc's. should be job done.
the pc's should have an IP address begining with 192