If you have a TV tuner card and the included program is very basic or it is not compatible with your PC, then you need an application like CRNTV.
The program supports cards based on BT8x8 (most recent tuners are made using this model), Conexant CX23881 and Philips SAA713x.
With Credits you can watch TV on your PC, manage all channels, even record programs that you want to keep. The program supports channel auto-detection and includes, teletext, zoom controls, sync quality and so on.
Even more, with Creative, you can see images from a digital camera or VHS player, as long as your tuner includes a video in input.