I tried giving one of my old ones, and it didn't work. They said if it's expired, it's expired, and there's nothing the person could do about it. Even when I said I fairly recently got the game that came the with expired card.
My XBL one year pre-paid subscription thingy was "expired" when I got it, but the code worked right away with no problem. But I guess the pre-paid codes work differently then the free trials.