After effects help please?

I am not new to After Effects but I am fed up with this jitter problem that I have. I am running After Effects CS3 on a Windows XP desktop. The footage that I import is .avi or .mov and I render out to a medium quality .mov without audio at 29.97 frames per second and at a 16:9 aspect ratio. I open the footage in my other editing programs and there is a jitter/playback/grow/shrink that happens to all the layers in my project. What can I do to fix the problem? Here is one test I made to show you. http://www.youtube.com/watch?v=OCymu6xIgfQ. My Email is myshorts.videos@gmail.com if you would like to contact me. Thanks.