I am really confused.

I have a single tuner Series2 TiVo and had to get a new Comcast cable box today. It is a dual tuner box. Is it possible to use the DVR capability of the cable box in addition to TiVo? It seems to me that if I set the cable box to record something, TiVo may change the channel when it wants to record. Does setting a recording on the cable box default to the second tuner and assume a channel change (from TiVo or otherwise) is for the first tuner?

Ideally, I would like to use the cable box independently of TiVo (everything goes to an A/V receiver). I think I would have to use the RF out on the cable box to TiVo and the RCA-type connections from the cable box to the receiver. I would then send RCA connections from TiVo to the receiver and select either "TiVo" or "Cable" on the receiver. Is that possible? If so, is there a signicifant quality loss sending RF to TiVo rather than RCA connections.

Thanks for any suggestions at all.