You should not use FormsCentral to collect credit card information. Please see Randy's response from this post: http://forums.adobe.com/thread/978301
"You shouldn't collect credit information directly using FormsCentral because we are not PCI complaint (we are not certified to store credit cards). Our PayPal integration is the way you should collect money."
Here is an FAQ on security: http://forums.adobe.com/docs/DOC-1384