play two external swfs; first one plays while 2nd loads

[gwu]

lets say I load an external swf(external1.swf) into a movie into a movie clip called "the_one". How does the main timeline know when external.swf has finished playing. Basically I need the main timeline to play the first swf (external1.swf) while the second swf is loading and then play the second when the first is finished even if the second is still loading.

_root.createEmptyMovieClip("the_one",1);
_root.the_one.loadMovie("external1.swf");

_root.createEmptyMovieClip("the_two",2);
_root.the_two.loadMovie("external2.swf");

thanks