Use what you're most comfortable with. In the end, your users don't care whether the site is using DIVs or TABLEs, they care that your site displays correctly in their browsers and loads quickly. I think there are instances where you're better off using a table, in order to avoid excess of css and markup that a div solution requires. Sometimes tables give you a quick solution for something tough or impossible to achieve by means of just css. In those cases I go for tables. People disagree on this point, though.
So what do you recommend building E-commerce site selling products - table or <div> or combo of both? ( BTW database is in Mysql and shopping cart is OSCommerce)
I always use CSS for my sites, but they need to look professional and not be full of pointless code, making it harder for a search engine to read. The only time i use tables is if i want to put some text into a small one, but i would never make a site just using tables because the code will look a mess.
For E-commerce, your site should be in semantic elements (HTML elements) and no tables for layout... however for the actual product listings, set up like a catalog, with product name, features, accessories, prices, etc. is likely a perfect table candidate. But again I warn you, if you use a table, use it the right way. Make that price <td> have references to the product (using "scope" or "headers", and a proper thead/tbody setup). Otherwise you've just got a jumble of td's floating around and that's not really any more meaningful than a bunch of divs floating around the page either. Use the correct tag for the content.