The answer is both YES and NO...
The use of SSL allows your customers to securely submit information to you via your web site (such as a credit card number, or other sensitive information). The key functions provided by SSL are data encryption and server authentication. Internet users have come to expect this level of security when making purchases on the Internet. Therefore, by this standard - YES, an SSL Certificate gives you the data encryption necessary to accept credit cards on your web site.
Since SSL is an encryption and authentication tool, it does not in itself provide the software or means to process credit card transactions for payment through a financial institution. The actual processing of credit card numbers, expiration dates and cardholder information in order to receive payment of funds to be deposited in your bank account requires a credit card "Merchant account" from an accredited financial institution. Typically this is a service that your local bank or other financial institution would provide in conjunction with your business banking accounts. - Updated: December 24, 2002