Setup Box or Computer Based?
I believe you can find Tivos but not sure if they have tuners as well an d they can get pricey.
For standard service you can get a computer (often with Windows XP MCE) with a built in TV tuner card that you can plug into cable.
If you have the right computer that can Tune HDTV/Analog/Digital TV and output S-Video or Component you can use the computer to run the TV as well...
There are tons of things out there and the decision process is tough. For a geek you can check out avsforum.com and come up with solutions for building your own (HD MythTV / MCE box). Or for the non-geek you can find a company that specializes in media center PCs and run with that.
Unfortunately, the options are endless which means decisions are tough too
I am working on a system to watch HDTV over the air and delay signing up for other HD packages until later after the COX / Verizon dust settles
Google tivo forums, gdty forums, htpc forums (home theater PC) ... Be carefull, you can create a monster