|What exactly are you trying to do? Are you trying to switch between multiple computers, or one computer and a TV? Are you trying to display what you want on the computer or the TV? What kind of TV do you have? What inputs does it have?|
Are you talking about a TV tuner PCMCIA card for the laptop?
If you want to display both a laptop and a computer on a separate TV, you can get a VGA to TV box for about $30, then use your TV as the switcher to go between computers. (Those boxes typically have component and s-video out) so you would put one on component in and they other on video in.
If you want to use the laptop as your TV display, then you need a TV tuner card (you can get them USB at newegg), and hook your digital TV box up to it, then use whatever software that comes with the tuner card to watch it on the laptop.
If you display one computer on the TV, and use the laptop normally, you can also use a program called Synergy to share the laptop's keyboard and mouse and control the other computer (that's displaying on the TV). Synergy is freeware.