[Magicjefferson25]

Well, just a word of advice. DON'T PUT A CREDIT CARD ON YOUR ACCOUNT!
Once that you put in the information, that credit card is stuck with your account for life, just don't do it.
And once your gold subscription runs out and you have a credit card on your gamercard then xbox LIVE automatically charges your Credit card for a 1 month subscription. It sucks, believe me. All it was, was a big headache.

You can change the credit card info by going to Microsoft's billing website. I had to do it today because my credit card expired. All you do it add the new credit card and info and it will automatically drop the previous one. As far as it charging automatically on your card when your membership runs out, you can cancel it if you choose to, but it renews it for another year not just a month of live.