Where to preloader(s)?

I have a main site (index.swf) that I load external flash movies into by clicking a button in my main site. For example, on my photos page, if you click a button it will load an external swf (petpics.swf) onto the stage for a picture gallery. I want to put a preloader on the external swf so it shows the user/visitor a loading progress bar w/ transition (mask??) until the external swf loads completely.

My question is, do I put the preloader graphics and code in the external swf or do I put them on the main site and incorporate the code into the button code?

Here is what I mean: my site http://rberry883.home.comcast.net – click on the Photos button and then on the #1 button on the right side which will load the picture gallery.

What I want to end up doing is having more buttons like the #1 button that will call different external swf’s that each have a preloader when one of the buttons load.

Hopefully that all makes sense and someone can help me out.

rberry88