Ecommerce Website

I need a fully functional e commerce website using shopping cart to sell fashion goods with the ability to take various types of credit cards and paypal. I need the css based design XHTML validated from w3c and be optimized for search engines. You will need to show examples of previous work and also explain the type of shopping cart to be used and the reasons you would choose that option. Options required are the ability to add products by by design and category, list similar goods available and items available on special. The system must be simple to add / edit goods. I also require that the shopping cart support third party payment processors such as eWay. Any suggestions will be appreciated. thanks