Choose a card to subscribe to Xbox Live, has the main advantage safety by avoiding using her credit card and go fairly sensitive information on its console. It will be remembered panic when there was intrusion into information of player accounts at Sony ... Second advantage, you avoid the automatic subscription renewal accompanying the payment by credit card. Option you can delete only the caller. It is binding and is quickly forgotten.
On the other side, it's a little more expensive it's true but it's the price of the price of peace.
Attention not to return the code provided by the card other than the Subscription menu at XBox Live, otherwise the code will be converted into points. These points are used to purchase content, but can not be transformed into subscription. Once back, it's too late.