One might ask how many devices does he want to connect to the internet. All via ethernet cable might be easiest. If he has 4 high speed switch ports and a single uplink port on the comcast and if he has 4 or fewer devices to connect then just use the comcast router.
If he has more devices than high speed switch ports then add the netgear router.
heres the pics i tried to drop frm gmail unsuccessfully earlier... maybe thatll help you gentlemen out....
http://postimg.org/image/4ss9hvja5/6e93b713/http://postimg.org/image/4rm34ogq5/fa5f5c12/http://postimg.org/image/5kyoxamr1/f996df4f/now of course ive obviously changed up that one ethernet connection in between the comcast and netgear to the regular lan from that designated internet port....