So your buddy with the new plasma TV won´t shut up about how great the game looks in high-def. He´s right-it is like watching a whole new sport. But you don´t have to splurge on a 50-inch flat screen to quell your HD envy. Stations across the country broadcast HD signals over the air, absolutely free. And since most laptop screens already have enough resolution to display high-def, all you need is an HD tuner that plugs into a USB port on your Mac or PC, and you can enjoy the ultracrisp picture at home or away. Let´s see Mr.