Authorize.net is one of the most trusted internet credit card gateways in the World.  Currently you can submit your payment using Visa, Mastercard or Discover Card.  Unlike Google Checkout, Authorize.net does not retain your credit card information.  You will need to re-enter it each time you make a payment thru this gateway.  This is one of the most secure gateways and uses a high encryption to prevent credit card fraud.