To watch or record TV on your computer, you must have three things:
A TV tuner
There are many types of TV tuners, from expansion cards known as TV tuner cards to external TV tuners that connect to your computer through a USB port or IEEE 1394 port.
Some computers come with TV tuners. If your computer does not have a TV tuner, you might be able to add one. Go to the Windows Vista Hardware Compatibility Center website for a list of TV tuners that are compatible with Windows Vista.
A TV signal connected to your computer
Depending on your TV tuner capabilities, it might be possible to connect a TV signal to your computer from an over-the-air antenna, a cable jack in the wall, or a set-top box. The types of TV signals available in your region will vary—contact your local cable or satellite provider for more information.
Software for watching and recording live TV
There are several options for software that will enable you to watch and record live TV on your computer. If you are running Windows Vista Home Premium or Windows Vista Ultimate, you already have what you need: Windows Media Center. If you don't have Home Premium or Ultimate, you can either upgrade to one of these editions of Windows Vista or install a third-party application.
For more information, go to the Windows Vista Help and How-to website
and search for "TV Tuners," "TV signals," and "Windows Media Center."