Customize shopping cart

I'm building a web-hosting site. I want an already available free shopping cart customized to fit into a theme that I've built with FrontPage. (See the uploaded .htm file) For example, every page displays the same top banner and the changing cells appear in the large lower right cell or table. You can use osCommerce, or Agora, or any other (free) cart that can be installed on a server that supports the script(s) used, e.g., PHP. There will only be 4 products to start, each being a web-hosting plan. No need for shipping costs. I must be able to add and modify products, pictures and text. I prefer additional pages rather than try to pack too much information on one page. (Most web-hosting sites try to look like the classified section of the N.Y. Times!) I think most of the custom work will be to remove all of the junk on the default front page of whatever cart you recommend! The cart must accept credit cards and Pay-Pal. I have not yet set up a real-time credit card account, but I will. I expect that the cart will have the ordinary shopping cart features, like email notices to customers, etc. Remember I want one of the existing available carts customized...I do NOT want an entire new cart design. I also want all the source script, etc.