Load & Unload Movie: How?

I might have been too wordy in my last post asking this question: How do I load and unload a movie clip in Flash 8? I’m digging as deep as I can through all the tutorials and threads, but I can’t find an answer to my question. All I want is for a movie clip to load when a button is clicked, then unload and be replaced by another movie clip when a different button is clicked. Any help is appreciated.