One of my colleagues just IM'd me with the following: "Did you see there's a 1-minute clip of 'Twilight' online???? OMG OMG OMG OMG OMG." While I suspect he was being just a teensy bit sarcastic with the "OMGs," there is indeed a nice little one-minute clip up over on MTV of part of the scene at the ballet studio with James going after Bella, and Edward coming to the rescue. It's a short clip, but it definitely gives you a feel for how director Catherine Hardwicke is handling the action of the vampire fights, and it's pretty intense.
It's just enough to whet your appetite a bit for the full scene up on a big screen ... and of course, by that point in the storyline, there will be plenty of dramatic tension from what's taken place before that to up the intensity level even more.