I want to accept credit card payments with global cart

Hi,

I just purchased MarketPress eCommerce. I am running WP multi-site at http://www.nuggetweb.com, and would like to use the global cart for user's shops.

When I turn on the global cart it says that I have to use Paypal Express Checkout. From my understanding, guests cannot checkout with a credit card this way.

Is there a plugin that I need, or a setting that I missed? Can I use PayPal Standard, Advanced, or Pro?

Thank you.