Thanks Scott. The article was helpful, but I'm still slightly confused. Do I create it in Shopping Cart Creator, save it, then open it up in Shopping Cart Designer and design it?? Or have I really got the wrong end of the stick??

You build your shop in the Cart Creator and save it there - so you add your products, Home Page, About Page, and other Page content.
You design your theme, or make alterations to the themes in Designer and save the theme which you would then import into the Cart Creator. Both can be open at the same time, and you can be working on both at the same time, but sometimes it's easier to work on one thing at a time, especially when you're starting out.
So you can, in theory, build your whole shopping cart in the cart creator, but you're stuck with the default themes. If you want to work on that first, you can work on a theme later as it will import into Cart Creator with all your work that you've done, or work on the theme first, then build the shopping cart. They are both separate programs that will integrate later.
