Sony and Nintendo came out swinging with handheld game systems at the E3 expo. Round 1: Sony announces the PSP (PlayStation Portable), due out in a year. Not only is it supposed to give the Nintendo Game Boy a run for its money, but the PSP will also play music and movies. Round 2: Nintendo says its next Game Boy won't be a Game Boy but something called Nintendo DS. The DS stands for dual screen: one screen to watch the game on and another touch-sensitive screen to control the game. Round 3: the PSP prototype is unveiled at E3--though with few details and no playable games. But surprise! The Nintendo DS prototypes show up at E3 with cool dual-screen games, like air hockey with a touch-sensitive puck, and chat capabilities. Our verdict: Nintendo DS by a knockout.