An event which shows a gif would likely place the gif on top of everything else (if I recall correctly,) which is the opposite of what you want. I'd say try for a gif as the panorama.
Then again, I don't recall if .gif is an acceptable format for a panorama.
I seem to recall that there was some script fro XP which allowed you to make backgrounds move like you could in earlier versions. I think that the name was something like "Parallax Background." You might want to search through Script Analysis, since I think it might work for your needs.
EDIT: Found it. I'll PM you.