Couple of quick comments (in no way consider this exhaustive):

- Optimise your title tag with the relevant keywords, lose the tagline (sure use it for offline media, but it's not very effective taking up valuable SEO space on the web)

- Add H1 tags as above.

- Cut your meta keywords tag to about 1/10th the size (not vital but but good practice).

- Modify your meta desc tag to sell your site better, don't repeat your tagline

- This is bloat, lose it:
<td class="link" onmouseout="this.className='link'" onClick="parent.location='about.php'" height="20" style="font-family:Verdana, Arial, Helvetica, sans-serif; font-size:10px;">
<font color="#666666"><b><a href="about.php">About</a></b></font></td>

- Table based layout sucks.

- Basics like using alt tags, etc.

Considering you're using database ids so frequently I'd give strong consideration to purchasing mod_rewrite enabled hosting.