Ok, so I have all these video files that I made from my sony camcorder. And they played just fine on my old computer running windows XP. Recently, I moved my harddrive to a new computer running vista, and to my (brand new) macbook, but I'm having trouble playing the videos. In vista, the video will play (at a slow framerate) and with no sound, and on the mac, most of the videos won't even open. I'd say about 5% of my videos actually work. I don't understand what the problem here is, since these videos were uploaded straight from my camera to my harddrive. Can anyone think of a possible solution to this? The best I can think of is opening them up in windows movie maker, and reformating them, or something. But I'd rather try another approach, as reformatting 20gigs of video seems rather tedious to me. any help on this matter, much appreaciated.