When you can display the fact that you have an X509 certificate on your online retail site, it says a lot about you as an online retailer. Displayed as an SSL Encrypted logo, this certificate lets your customers know that you are very concerned with protecting their personal and credit card information. What it essentially says is that you have taken the best possible steps to ensure that their information is safe from hackers and identity thieves.
The X509 certificate is your way of letting every customer know that you are using the very latest SSL encryption that requires both the public key and the private key to decrypt any information that has been entered into the payment form. What you are going to find is that the average customer today will not use a site that does not offer this level of security on their web sites.