Menu popups inactive over images/content. How can I get them up front?

Hey all,

My menu popups at http://www.waterscatering.com/ are inactive images/content/. How can I have them show up in front?

Originally, it worked fine in Firefox, and the popups hid behind the content in IE. Then I started playing with position and z-index, and got both browsers to display the links fine. However, not in both browsers, it just pops over, but clicking them acts on the images and content below.

How can I make them popup in front, and still be active?

Thanks!
Adam