You have a bunch of style and script tags before the actual HTML document. Those should be in the head tag of the page.
The doctype tag has to be the first tag in the source, otherwise IE will render the page in quirks mode. Other browsers may also render it in quirks mode, but it makes a lot more difference for IE. One big difference is that the box model is handled incorrectly.
Once you get the basic structure of the code correct, you should validate the html, and the css to see if there are more problems in the code. I can see right away that you have an HTML doctype but you are using XHTML tags in the code.
If the menues still doesn't work after cleaning up the code, I would guess that it's a problem with the z-index so that the menues show up but is hidden behind the main content. IE doesn't handle z-index correctly for elements that has layout.