Should I tell you what Zen Cart is? I don’t think it is needed. Still if there is really someone who never heard about Zen Cart, the following lines are quoted for you from Zen Cart’s website :
Zen Cart™ truly is the art of e-commerce; free, user-friendly, open source shopping cart software. The ecommerce web site design program is being developed by group of like-minded shop owners, programmers, designers, and consultants that think ecommerce web design could be and should be done differently.
So you now know that Zen Cart is a fantastic shopping cart system which is free and freedom, implies open source. Using Zen Cart you can develop a fully professional e-commerce website without hassle. Please visit official website to dig more of it.
Visiting and researching the website of Zen Cart you probably are convinced of using it for your e-commerce site. But I see your forehead is sweating as you are thinking about the hassles of integrating it with your current website. Huh, its not really a matter to worry about!
Mr. Shureed Sarkar, author of Zen Cart Book, has published an article about this integration of Zen Cart with existing CMSes which surely will remove your previous worries! He discussed how to integrate Zen Cart with several CMSes like Drupal, Joomla/Mambo, Gallery2, WordPress, Xoops, e107 etc.
I believe you may find this article very helpful if you looking for help to integrate Zen Cart with your current website. But if you need to learn about Zen Cart quickly, his book may be the best guide for you.