Star Wars: The Force Unleashed Trailer

This appears to be the Star Wars game to rule all Star Wars games. The intro to this trailer takes the "size matters not" adage to a new ridiculous(ly cool) extreme. The focus of the game appears to be using force powers to take out enemies, where most past Star Wars action games have focused on blasterplay and saberdueling. What I don't get is if the main character in this is a light-sider or dark-sider. He's got all the telltale signs of the Sith: dark clothes, red saber, force lightning... And we hear Darth Vader rasp "You have done well, my apprentice," so it would seem we will be playing as Vader's apprentice. BUT, the whole trailer he's killing Stormtroopers and Tie Fighters and such. I'm very confused, and crazily excited!