Specialist Ecommerce Designer

We are looking for a designer who really understands how to design for ecommerce websites.

We have an ecommerce site that is now in its 10th year. We have been working on a new, completely rewritten version of the site for the last 8 months and now we need to find a designer to create the skin for the site... to make it as efficient at converting visitors to customers as it can be.

We have a lot of knowledge in-house... but we can't find a designer who really 'gets' the specific usability requirements of ecommerce.

Please provide examples of similar projects that you have worked on in the past, and start your response "Dear Sam" so I know that you have actually read this spec (even though that's not my name!)