The key design goal of Apple was to create a notebook computer tough enough to stand up to the occasional bumps and other unexpected mishaps of life on the go. From the standpoint of a laptop, the inside of a backpack can be a very inhospitable place. And yet you shouldn't have to walk softly just because you're carrying the most appealing notebook ever.So, the iBook's sleek case is made out of impact-resistant polycarbonate plastic. That would ordinarily be sufficient to survive the rigors of everyday use and abuse, but that's not all. Inside, a sturdy magnesium frame provides superior strength, while reducing the iBook's weight to well below that of other full-featured PC notebooks. There is even a rubber-mounted hard disk drive for added bump tolerance, so you can store all of your digital goodies on your iBook and still enjoy peace of mind. Additionally, the iBook has no I/O doors, protruding latches or levers to break or snap off when tucking it into a backpack or briefcase.