Have to buy an aerial splitter first, as unlike every other STB on the market the Tivo seems to lack an aerial pass through for the TV
Once you've got the hang of TiVo, you won't bother with live TV anymore. Just plug the aerial into the TiVo and forget the TV's tuner (as we have).
you will need the normal tv tuner though, if you want to record two shows, and watch a 3rd.
But of course the 'third show' will be something you recorded earlier ;) It does take a while to get out of the mindset of watching something "when it's on".