If your site accepts credit cards over the Internet, you are required to be PCI compliant. This means your servers and application(s) must satisfy a set of criteria outlined by the Payment Card Industry (the credit card companies.) Although there are services out there such as McAffee and TrustKeeper that perform the scans, they have a high false positive rate. This means they report problems where none exist!
I have quite a bit of experience with PCI compliance remediation and can help you weed through a scan report and tell you what changes you need to make in order to become compliant. I can also take care of the whole process for you, completing the work and allowing you to get back to running your business.
Contact me to get help with PCI compliance!