I would change from cable to satellite if at all possible. The PQ is better on all channels.
MidCow2
Now I wouldn't say that as an absolute fact. Maybe in some cases it is true but in my experience I have found cable PQ to be on average better than satellite. Theres a hard line sending the video/audio information as opposed to satellite signals. As a result, I have found there to be far less interference in cable than satellite. That said however, some cable companies are good, some are not. Here at school, we have Cox cable which I find to be excellent. We have a lot of HD channels and the overall quality is good. However, at home at my parents house (about an hour away), they have Charter cable which is horrible. They are missing HD channels such as CBS and FOX which I think is inexcusable (especially if you like to watch football). So in conclusion, I suggest that if you have a good cable company to go with cable, if the service is poor from your local cable company, satellite would definitely be a better bet.
Now as for HD Tivo, from my personal experience with both Tivo (non-HD for me) and cable company provided HD-DVR, I would definitely go for the cable company DVR. Now I am not bashing Tivo in the slightest, it is by far more functional and has a sleeker interface but the added costs is not worth it to me. Also, Tivo tends to degrade the picture quality since the signal is first going to the Tivo box and then to the TV. Maybe this has been fixed or improved but I have not seen it recently. The cable provided DVR may not be as sleek or have as elegant of an interface, but it still does all the same basic recording and searching functions that Tivo does for considerably less money.