Another one of those "works in FF, not IE" threads
Wow, didn't realize how many people's webpages don't work in IE. Well, that is my case too. Anyway, I was just wondering what creates a small bit of white space in IE, yet does not pop up in Firefox. The website is here, and the style sheet is here.
I'm going to assume that extra space to the left of your nav_container. This is a bug in IE known as the double margin bug, it occurs when you add a left or right margin to an element that is floated left or right. Add this to your CSS