I have a Compaq Presario PC running Windows XP with Microsoft Works. I maintain about several thousand files on the computer in Word for my home based business. I have purchased 2 16G SanDisks in order to run a full backup of my whole computer system, but I cannot get the whole system on these 2 16G disks. They both indicate that they have space left on them and a fair amount of it. So why is the first disk not being completely filled before asking for another disk? I am NOT a technically savvy person so explain in simple terms please. THANKS!