You know what I did?
Cancelled my cable but kept the internet (much like you are) you still keep all analog channels and clearqam.
I am sure there is someway they could stop it but this works for me. Hell I even still have DVR functions using windows vista and two 360s as extenders.
quality is definately down, since I don't have clearqam support yet, but it works for the amount of tv I watch.
and yes comcast is evil