I have a site up and running at http://www.parkschoolitclub.com
The naivgation (sliding) works in all browsers, properly on all platforms. However, put the blog on IE6 and the sliding navigation dissappears, but is there in FF, Safari etc.
It only happens in IE6 and below (no-one tested on IE7, can anyone confirm?). THe styles are sloted into the normal styles css sheet (http://www.parkschoolitclub.com/blog/wp-content/themes/psit/style.css)
Other than that you should have all information needed.
By the way, the edited header is simply header.php from the psit themes folder.