I was hoping someone could guide me in making the correct decision regarding integrating my existing domain with a hosted shopping cart. I have an existing website to promote my bricks and mortar retail operation and am expanding into web retailing. I will be using one of the major hosted shopping carts. What is the best way to join the two components from an SEO perspective? Have the cart as a sub domain of my main site, or move my existing domain name to be hosted by the cart provider and have both components operate under the same general domain? I have read arguments that putting your cart within a sub domain is not a good idea because any clout of the pre-existing domain will not be shared with the  sub domain; that they will be treated as two separate sites. I have also read that using a sub domain is a good idea being that the content focus of the main domain (marketing and blogs) is different form the focus of the sub domain (product sales), and that the two components would benefit form earning their own rankings undiluted by the other. And, I have also read that search engines are getting good at being able to deduce that an eCommerce sub domain is legitimate extension of a content intensive main domain, and that they treat the two components as a combined whole. What is the truth? Which is the better way to go? Any guidance would be appreciated.