I have set up my stores using the Pay Pal Pro method - where you need to enter your Pay Pal API information (such as user, password, and signature which are granted when you request an api in your account)
If you use Pay Pal Pro, it will accept credit cards and use Pay Pal as the gateway to process. The user also has a choice at the top to just use the Pay Pal express method as well.
Regards,
Brian