Fortunately, Comcast is forced to allow competitors to access its cable lines. Earthlink, one of the evolved dial-up ISPs, resells Internet access over Comcast's lines and a comparable rate--both in terms of price and speed.
Earthlink has surprised me in a few places; not everything is good, but it's not all bad either.
Starting with the set-up, I was forced to pay about $50 for Earthlink to send out a Comcast contractor to do an "installation" that amounted to the contractor reconnecting to cables in the garage and reading the number off of my cable modem. I also got a 3' length of cable out of it.
The first time the modem came up, it was on the Comcast sandbox network. The modem then reset and I came back up with an Earthlink IP. That was it. With Comcast I'd needed to talk to somebody with a thick accent before getting out of their sandbox.
I'm also happy that my e-mail is working again, something that Comcast had broken about two months into service.