n00b - Accordion like question

Sorry… originally posted this in Kool Sites for absolutely no reason whatsoever.

First let me say, hello. This is my first post. I am a Flash Hobbiest, who has built a few sites for friends, but who still has a lot to learn.

Here is a site I built for my buddy. www.mattguntherphotography.com

There is a particular effect that I am certain is quite easy to create and yet I don’t even know what to call it. The most basic example would be something like this:

Four Boxes lined up horizontally on the stage. When the cursor is over the box it resizes to become bigger and the others make room accordingly.

How do I create this?

thanks

thanks