We do not charge preorders until a beta (or for those who order after the last beta for a game, the final) is made available to you. So right now, the most you will have is a 24-48 hour hold placed for the amount, though hold policies vary from bank to bank. Until it is actually processed, your order is simply waiting in the queue.

In order to use a prepaid card, you will need to have a sufficient balance for the preorder when the time for the beta to begin arrives (late spring or early summer is the plan right now, AFAIK). If at that point the card is too low or has expired, it will fail when we attempt to process the order.