Hard to say w/out knowing a lot more detail. I might go at it- one weblog for ‘products’- each item goes in as an entry. If there are only a couple of images max, I’d probably just put them in custom fields- say have 5 images fields and an image url in each. (Or I might have an ‘images’ weblog, each image is an entry, a relationship field so images can be related to a given product). I’d probably use a plugin to handle image resizing on the fly.
Categories- would be stuff like women’s shirts, men’s shirts, pants… Totally varies depending on the type of content.
But there are likely a lot of different ways to go at this one.