Magento

I am working on an e-commerce site where they require a horizontal navigation. In this navigation will be images (Product Categories, Brands, Help Center, Sales, Contact Us). The Brands and Product Categories are going to be two separate Magento categories with drop down listings (sub categories).

The default template uses text for the drop down categories. I need mine to be a image drop down, and then the listings under the drop down will be text. How do I do that?

Also, there will be a left sidebar navigation that has a listing of all product categories (It will list the same thing as the drop down).

How would I go about listing both of those? Thanks.