it hink paypal is the best option for beginiers who dont want to spend a lot out of pocket, and do not want to have to set up secure gateways and all that stuff.
I use paypal pro which is $30/month but the customer does not NEED to go to paypal to pay. The customer doesnt even know that they are using paypal because it works like a payment gateway, but it also gives them the option to pay with paypal if they so choose.
As for shopping cart software, i chose the one with the best support forum. I chose oscommerce. It has a crappy out of the box look, but you can do a TON with it..There is also Zen Cart which is another favorite..