I'd like it if switching between the tabs was handled via Ajax, rather than a full request.
The good part is that you've done things right and built it without Ajax to begin with, so you can just Hijax (http://domscripting.com/blog/display/41) the links.
Edit: The "Return to top" link could also be a link to an anchor, rather than a link to the current page's URL.
Edit: The "Return to top" link could also be a link to an anchor, rather than a link to the current page's URL.