E-Commerce Store

Hi,

I researched a lot of E-Commerce on-line services: Yahoo, Monster, IMS,
eStore, you named.

For my case, integration with an existing inventory and orders systems
is a must.

I don't want to create my own e-Commerce environment, I want to use an
external service.

So, Do you know an E-Commerce storefront that it is strong in how it
can be integrated to existing applications?

For example, it would be great if the storefront solution offers Web
Services as a way to export/import inventory, orders and customer
information.

Thanks,

Norberto