Trouble with Divs - can't get the divs to scroll properly... Overflow Hidden & Scroll

Hi,

I'm a little out of my deapth, and running out of time...

This site has a scrolling div within an overflow div.  I want the page to be fixed size, wirth the footer at the bottom, but for the content to scroll.  Then I'm using jquery to change the text as images scroll into view.

But I can't get the container div the right height...

http://www.sarahhardy.co.uk/index.php?page=3

Depending in your screen width, you will see only 2, 3 or 4 images in the scroll (there are 4) and you will see that the scroll bar doesn't stop at the bottom of the page.  (on Mozilla - not checked cross browser yet...)

Quick fix?

Thanks

Cris.