Integrated preloader issue

Does ANYONE know of a good book or tutorial that talks about preloaders in depth, or could shed some light on the issue. I think it’s one of the most important things in Flash, yet everything on the web seems to only discuss parts of different ways to do it. I think a beautiful example of a great preloader is http://www.24-7media.de/BWS. It seems as though it’s integrated in the main swf, It’s always in the same spot, always the same preloader. As opposed to the way I have done it http://www.versing.com …apreloader for every movie I call that shows in the movie to be called. I feel like there has to be a better way to do this. A way that would work like : http://www.24-7media.de/BWS/

Thanks for any help!