Redesign of oscommerce jewelry store

I am running a jewelry online store templated by oscommcerce. I am not satisfied with the current design for my store, and need to change a new and fashionable skin. I require you to integrate this new design with the currently running website, wihtout damaging all data including our product and customers'data. no affecting our online business on line. The new design will not affect the good ranking of SEO performance of my site. Please take SEO into account in the redesign of the website. At the same time, we need you to fix some small problems at the site. We need a very very professional freelancer to do this poject. The designer who can give free mockup will give the first priority of consideration.