Prevent preloading if already loaded

Hi all what is the best way to prevent preloading if already preloaded.

I have a flash footer, which inlcludes a preloader. But the problem is because its on every page the preloader happens all of the time.

I need a way not to show the preloader if already loaded.

So in effect the clip should preload once and never need to preload again right?

Any help greatly appreciated

Thanks