Can we see this in action ? Have had the same problem several times but all different causes.

Had a quick look at it. I guess it's a problem with margin's and padding. IE6  renders it different than IE7 or Firefox.

What you can do is define different padding and margin for IE6 and IE7,ect..

CSS example

#content
{
padding: 15px;
margin: 0;
}

html>body #content
{  
    padding: 10px;
    margin: 5px;
}

The second style rule is not recognized by IE6 but by most other browsers. You would probably be better asking thit in as CSS-forum.