Preloader and loading external swf

Hey all,

So I have setup a mini flash site. I have some buttons on the right - then a movie clip called ‘container_mc’ - currently there is a button at the bottom. When you click it - it loads a preloader - which loads an external swf file. It works beautifully - but I want to change it around so that instead of having to hit the button - when the page is loaded - it starts the pre-load instantly and the swf file will eventually play.

Here is the code currently off the button :

        replay_btn._visible = 0;

// movie 2 loads the tankturn swf using startPreload
movie1_btn.onPress = function(){
        replay_btn._visible = 100;


// this function begins preloading a swf url
function startPreload(url){
    movie1_btn._visible = 0;
    tunein_info._visible = 0;

    // use loadMovie to load the swf url into container_mc
    // attach the preloader animation
    // this will be removed when preloading is complete
    attachMovie("preloader anim", "preloader_mc", 500, {_x:130, _y:120});
    // set the onEnterFrame event to call preloadContainer
    onEnterFrame = preloadContainer;

Would I be able to create an onClipEvent(load) type of action, because I tried that and the preloader just goes around in circles and the swf never loads.

Can someone help me out?