321810 Magento Site/ shopping cart

We have created a look/design for an update to our current online store. We are adding new products that have multiple options so we need a layered store design (e.g. Sunglasses: you can choose from 3 color frames, then you choose from 3 colors lenses, then you choose from 3 sizes). We believe Magento (free software) can be perfect for this. See current store (buildt in OScommerce) [login to view URL] We need to be able to do back-end updating ourselves (putting specials, change shipping cost, adding or removing product etc).