Okay, well, sort of. I noticed this past November Microsoft didn't charge me for my annual Xbox live subscription. Never one to look a gift horse in the mouth I just kept on playing. That is until I decided I wanted to purchase an Xbox live arcade game and needed to purchase additional Microsoft Points. Well, low and behold my debit card's expiration had come and gone way back in June.
So, for the past 6 months I've been gaming on Xbox Live without having a valid card. Not once did Microsoft send me a little note asking me to update my card or anything. aka, Microsoft rocks. Apparently, they'll let you continue playing without a hassle when your expiration on your card goes up. No doubt, they'll figure this out eventually or the user will just update his account on his own like I did. Regardless, I was pretty impressed.
Long story short, once you update your card with a new expiration date the charges for xbox live kick in but until then you're playing for free.
So, if you want to do the same look through your stack of plastic and find one with an upcoming expiration date, use that and then toss it. You can always purchase xbox live points at the retailer versus buying them online (wish I would have done that instead).