You need a TV tuner card $40~150 depending on fearures.
They come with PVR software, that is how they record off the air. Video files take up a lot of HD space you may have to get larger second HD. The mulitmedia fourm is a good place to find out more. john
I would like to record live TV but don't need all the bells and whistes you get with PVR. Does anyone have recommendations for what hardware is best for my 2.4gig Celeron with 512ram 40G HD computer.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic