Losing data to hard drive failure is a painful way of learning to backup, backup, backup. It happens, though, and happens quite often. It seems no matter how much people are told that the risk of losing data is there, they will still take the risk. After all, why buy two when you can make due with one? Often someone with multiple hard drives had to build their PC themselves, get it custom built or have it modified after the fact. Someone buying an HP or a Dell or a Compaq usually didn't get the choice, nor did they even know it was a risk! It's becoming more common, though, for OEM's to offer upgrades or machines with multiple disks. Two models from Gateway, for instance, offer 500GB of storage in 2 250GB discs (although any particular one could still go bad). The majority of new motherboards have some form of onboard RAID support, which makes it easier to offer things like this. Read up about this here.