What is the difference between billing systems and PayPal? Billing systems such as Verotel and CCBill are offered seperatly to PayPal on many sites and offer instant credit card payment, but isn't that what PayPal does too? Does PayPal require membership? Is more than one solution neccesary? What are the commisuion rates, monthly charges etc? None of the magitude of web sites I have found answers these questions. Thanks.