shopping cart with Google Checkout

I'd like to integrate my pre-existing website. I'd like to keep the design the same, but in the bracelets and earrings pages, I'd like to have a shopping cart that has some features. I'd like it to show the quantity available and a "buy it now." This will have this goto the google checkout. I'd like it to calculate shipping as well. Once the product is bought, I'd like this to subtract the quantity available by one, and if there was one left to say, "sold out." I have some ideas on how the layout will be of the product page, and I will send a template once the project is won. It's important that I can edit and add new pages and new products later on, and be easy to integrate again a different webpages, so It needs to be able to be flexible in this way. I'd prefer no databases, use cookies or XML for the cart. If a database is absolutely necessary, my server has SQL server 2005. There are about a million different free shopping cart codes, so the programming of it shouldn't be that big of a deal, but I just can't get this to work because I don't have a lot of experience in this field. Download what a general idea of what it would look like @ [login to view URL]