Foray into the unknown

You're never going to guess what I'm going to try! I'm going to (possibly) set up a shopping cart for a friend/client of mine who has the cutest shop and she wants to sell online. I found this nice site that does it all for you, but I have to learn the "insides" of a shopping cart! The site is Pappashop and it doesn't seem too difficult to manage.
Do you have an online shop? What do you use to checkout your customers? I'd love to hear your advice. It seems so much easier than setting up individual buttons on Paypal...oh, and I am learning some cute tricks....like a scrolling marquee in the sidebar! And I'm going to try to setting up rows of images with clickable links underneath in a POST!!!  Stay tuned for more HTML damage!