I started Comcast service about a year ago. They have a page of approved hardware on the web, and I bought a new modem off of that page. It seemed there was plenty of choice even then.

I happened to pick a Motorola SB6150. What surprised me was that there was not a shred of technical information or any management screen. After the cable was installed in my house, my brand new modem was attached to the cable infrastructure and then downloaded Comcast firmware for about twenty minutes. After my modem had completely joined the Borg, only then was it allowed to offer me internet service. Sigh...