Quick Preload Question

Yes, I know, yet another loadmovie+jpg+preload question. Please bare with me, I just need a pointer of how to load all the JPG’s using one preloader… I have one container MC (fotos_mc) that loads 36 different MC’s with JPG’s in them:

	_root.fotos_mc._x = 0
	_root.fotos_mc._y = 0

for (i=1; i<totalFotos+1; i++) {
	_root.fotos_mc.createEmptyMovieClip("foto"+i+"_mc", i);
	_root.fotos_mc["foto"+i+"_mc"]._alpha = 0;

I first tried to preload the fotos_mc but that didn’t work, it just went along to play the movie even though all the pictures were not loaded… does that mean I will have to preload each and every different picture MC? Can I just preload it’s parent MC, which would be fotos_mc.