Can't get video full screen

Ok so I'm using FRAPS (Full version) and I'm also using Sony Vegas Pro 9. Now, when I record using World of Warcraft itself, the video is full screen. (YAY just how I like it) but when I record using the Model Viewer; All of my video shots are this..crappy kind of 'wide screen'. I can't get the video to take up the entire 'canvas' in Sony Vegas (OR Windows Movie Maker for that matter). So if I have a background to my clip you see the shot.. but then it's surround by a big black box of emptiness. How the heck do I get my video to take up the whole screen? :( Any help is appreciated, no matter what settings I change I just can't get it full screen.