Need website updated, SEO, and promotion

We need a website upgrade. We are an automotive engineering company that specializes in automotive diagnostic software and hardware. We are engineers, but poor website designers. We need someone to help us upgrade our website so that it helps establish a good online business presence and helps sell and promote our current product. It also must be a flexible enough website so that our future products will fit. We want search engine optimization and help promoting the site and increasing the number of visitors and paying customers. It can be based on our current website or a completely new design. You will need to become familiar with our products and services so that you can help us provide meaningful content also. All pages must view correctly in Opera, Firefox, Netscape, and Internet Explorer. We might also be interested in someone to help us with some ebay sales and marketing. Probably on a commission basis. Please respond with a well thought out solution for serious consideration. Submissions without substance will receive little or no consideration. If we are satisfied with your work you will be recommended to one of our partners who is also looking for a website upgrade.