If you have a Series 1 or Series 2 Single Tuner DVR and want to continue receiving all of your channels, you'll need to connect your TiVo DVR to a TV Adapter or a Comcast TV Box.
To continue receiving all of your channels with a Series 2 Dual Tuner DVR, you'll need to connect your TiVo DVR to a TV Adapter or a TV Box from Comcast. However, connecting to a TV Adapter will not allow you to use TiVo's dual-tuner functionality. To do that, you'll need to use a Comcast TV Box and a cable splitter (included in the Series 2 Dual Tuner package).
Note: Only one tuner will receive your complete channel lineup - your second tuner will receive only basic channels.
If you have a Series 3 or above HD DVR and do not already have CableCARDs installed in your TiVo DVR, you will need Comcast to provide you with either:
Series 3 HD DVR: Two CableCARDs
TiVo HD or TiVo HD XL: Either one M-Card or two S-Cards