Thanks for the info. I assumed switching out of PPPoE would be all, but just wanted to confirm. So that's really the only thing to change?
From what I've been reading about Xfinity, they install a gateway modem (sigh). It can be bridged, but only remotely by the ISP, and most of there reps don't have any clue (bigger sigh). I took tomorrow off from work planning on dealing with this, and am prepared to go buy a cable modem (to replace their gateway modem) if I have to.