I do not see any reason redesigning from scratch your site. You already have tableless CSS for layout and XHTML for structure.
Therefore you only need to change your code structure to:
- Header
- Main Navigation
- Main Content
- Sub-Navigation
- Adsense Ads
- Footer
By the way, the first think I thought when I came to your site that it is a MFA site.
Those ads would rather be better on the right side of the page.
Adding breadcrumbs would improve your navigation.
Also you have too less content.
What you are sure doing, you are confusing blind users and search engines crawlers, as you do not have a correct document outlining. That mean's you are implementing your heading tags totally wrong (<h1>,<h2>,etc). Read more about this here:
HTML Tags and SEO
After all, the visual appearance does not look professional. But that is an off-topic comment.
That is all I could tell on the fly.
Good luck.
