Don't assume that simplicity means simpleCart(js) is lacking in features, though. You can price items in multiple currencies, and include tax rates. Your shopper can increase or decrease the number of a particular item direct from the cart, or remove it entirely. And there's support for selling your goods through both Paypal and Google Checkout.
And what's perhaps even more important, it looks professional, with embedded product images making it easy for your visitors to see exactly what they're buying. There's no sign of the rather basic underlying technology: simpleCart(js) looks like a powerful, expensive product.
Best of all, configuration is really straightforward. Just follow the documentation and you'll soon have the cart online, ready for use.