There would be something to say:
1. You don't have a DOCTYPE declaration, whitch I think is very important; you must correct that. Check
http://validator.w3.org/check?uri=ht...et%2Findex.php for details.
2. In your home and category page the title of your products are in H1 tags; using H1 is very SEO if you use it once on a page, usually the same or simillar to the TITLE tag of that page; using H1 many more times could actually hurt your SEO or even get you penalized; I suggest you put the category name in H1, subcats in H2 and product names in H3
3. The TITLE tag on product detail page: you lose a lot of precious space and character position with the product code: get rid of it. It doesn't help your SEO in any way and it pushes your keywords further from the start of the tag, which is very bad for SEO
4. The product images ALT tag: same as with the title - get rid of the product code from there; you could add the short description near the name of the product
You should aply these principles to all your pages.
A more subtle thing is the way your content is placed on the page: if you look at your code you'll see that the upmost thing on (all) your pages is the left menu which is veeeeeery long and the same on all pages, while your main content (product listing, details etc.) is placed near the bottom of the code. This is very bad for SEO.
If you would have designed your page with divs/css, it would have been easier to move the main content up and the menu at the bottom while preserving the page layout.
Since you designed your page with tables, the only way I see you can do this is by moving the menu on the right.
Remember: this is really very important for search engine optimization; think what SE see on (all) your pages: the first two thirds of the page is the same content, which is the menu... veeeeery bad !!!
Fix those things and we'll see further