shopping cart for book publisher site

I am the web master for a book publisher's site. Currently, all our books can be purchased by clicking on a link to Amazon.com. We want to start selling the books directly without Amazon, So I need a good shopping cart I can add to the already existing site.
does anyone have a recommendation for a good shopping cart that is easy to implement?

Which language are you looking for it to be in?

I know a few good php ones.

http://www.phpshop.org/
http://www.oscommerce.com/

are there any shopping carts written in ASP?

try looking here:
http://www.hotscripts.com/ASP/Scripts_and_Components/E-Commerce/Shopping_Carts/