This contribution validates the catalog side only under XHTML. Also took the liberty of correcting the following things:
* improperly nested tags
* missing start/end tags
* product_listing.php no longer creates urls with the category, only appends product_id to url. Search engines frown upon multiple copies of the same file, which is exactly how it appears as default.
* fixing all calls to scripts
* Relieving the stylesheet of the reduncy in attributes (font-family was declared 36 times!)
This is meant for a fresh install of ms2 as it is a direct replacement of files. Can also use a file comparison utility of course.