Data Encryption
There's no shortage of processors willing to store your CC info and exchange it for a token with which you can bill against the stored number. That gets you out of PCI compliance, but still allows on demand billing. Depending on why you need to store the CC, that may be a better alternative.
Most companies refer to this as something like "Customer Profile Management", and are actually pretty reasonable on fees.
A few providers I know of (in no particular order):
Unless you are a payment processor you don't really need to store any kind of CC information.
Review your requirements, there really is not many cases where you need to store CC information
Don't store the credit card numbers, store a hash instead. When you need to verify if a new number matches a stored number, take a hash of the new number and compare it to the stored hash. If they match, the number is (in theory) the same.
Alternatively, you could encrypt the data by getting the user who enters the card number to enter a pass phrase; you'd use this as an encryption/decryption key.
However, anyone with access to your database and sourcecode (ie. you and your team) will find it trivial to decrypt that data (ie. modify the live code so that it emails any decryption keys entered to a disposable Hotmail account, etc).