As mentioned previously, some Shopping Cart solutions will provide SSL as part of their services. If they do not, however, you will need to apply SSL to your website. This also applies if you opt not to use a commerical Shopping Cart solution.
SSL Certificates have an encryption value showed in bits. You should ensure that the certificate you plan on acquiring is of adequate encryption (eg. 128bit, 256bit, etc).
Certificates also have an expiry date and must be renewed at the end of this period. You should not let your certificate expire before you renew it, so as to ensure it does not reflect poorly on your company.
How Do I Get An SSL Certificate?
SSL certificates are created by several different companies, and can be purchased from a number of resellers. eWAY is a reseller of GeoTrust SSL Certificates, one of the biggest providers of SSL's in the world. Product details, and purchasing information can be found in our SSL section.