I would like to hear from developers who have a good portfolio of completed and fully working ecommerce sites.

I would like to use existing code you have developed rather than build an ecommerce site from scratch.

Our aim is to build an automated ecommerce site that integrates with our suppliers and automatically produces a shipping list for us to send to a warehouse that will then ship products.  The site has to be as automated as possible.

The admin area will integrate with the warehouse and have a warehouse management screen.
There will be a call centre application where orders can be checked or placed through manually.
Payments will automatically go to suppliers after authorisation. 
All transactions are stored automatically or can be exported to a UK accounting system like Quickbooks or Sage.

The site has to pass W3C validation and work in 
Firefox 3, 3.5
Internet Explorer 6, 7 and 8
Google Chrome
Opera
Safari
The site must be easy to template using only external CSS and images.

Ecommerce site will integrate will the stock systems of various suppliers.
Platform can be PHP or .Net. 
Would also be interested in an e-marketing application that could be integrated into the admin area like mail chimp.