Hurrah, built CSS nav bar! How prevent submenus showing in IE6?

Hi all

I’m so happy because I managed to build a CSS-based navigation menu (in the footer on https://philipus.com). Of course the submenus don’t display correctly in IE6.

However, I’m not interested in supporting IE6 so my question is how can I prevent the submenus from displaying in IE6?

I have an IE.css stylesheet – should I insert something there?

Thanks very much!
Philip