One thing that I am curious about to begin with is X-Cart. If this is like most product carts, I'm going to assume that it already has a redirect from your ROOT folder to another folder with all of you product cart files. If this is the case, adding another redirect is only going to make things much worse. Once search engnies (especially Google) pick up on the redirect, you have already lost some credibility with Google. To add another would be about as bad as having a mirror site on the same server. You should always optimize your home page (index.html, default.asp, and so on) to reflect you most highly regarded keywords and/or keyword phrases. In mmost cases your most important. Use your inner pages to take care of the rest. Finally if I am right about the initial redirect to a product cart folder inside your ROOT folder, I would take your index file from that folder and put it in your ROOT folder and update all of your PHP include tags to redirect to your product cart folder.

I hope this helps. L8r - Saxman