LOL. I could have easily written this myself.
The contractor did the exact same thing here.
When he finally left, I didn't have cable, internet, or phone installed. Somehow, it was supposed to just "magically" come up later that evening. I finally got the TV working on my own by calling and having Comcast set up the box remotely. The internet and phone (I kept ATT long enough for some overlap) took a visit by a "real" Comcast tech who told me that he spends all weekend fixing the contractors screw ups. He also said never to let them in the house unless they are driving one of the white vans or one of the ladder trucks. Anything else is a personal vehicle with a comcast magnet stuck to the side...
Also, to the OP, be wary of setting the account up online. I had a lot of trouble setting it up and was told to call an 800 # to start service. The 800 # on the COMCAST site doesn't always bring you to comcast - it brought be to an independent contractor who never actually placed the order. When I finally got through to REAL comcast several days later, they had NO record of my account being set up and said the deal I was offered doesn't exist. I don't know why they deal with these idiot contractors as their front line to the public. They must lose more business this way, I'd figure.
That said, I would agree with others that caution against a single unit. Routers are cheap and easy to replace these days. Also, if Comcast delivers on the promise to overhaul their network this year (I heard 50-100 Mbps), we may all be in need of faster routers (the modems should handle it fine, though). Also, check with your local office about compatible equipment. 1) In my area, I can only rent from them. They say they won't provision personal equipment, even if it is the same model # as what they support. Also, (2) what works for Comcast in my town is different from Comcast 15 miles away (different offices) and they don't always know what works in other areas, for some reason.
Anyhow, best of luck! And let us know how it all works out.
P.S. The Comcast support forums are a great way to get REAL help from their techs. My caller ID never worked right from the beginning (yes, the contractor screwed that up too!), but a post in the right forum got it escalated to the right people who fixed it with ease.
And a few older ones...