Hard drives are the last remaining fully-mechanical piece of technology left in your computer, but that's about to change. Solid State Disks (SSDs) are coming, and with this news, perhaps their prices will being to fall from the stratosphere.
These things are supposed to be much friendlier in terms of heat build-up and battery consumption, and now Samsung says their lifespan is well in excess of the usual 5-year MTBF for mechanical drives.
In a couple years, you'll be able to pick one of these up at Staples in a hurry when your current drive starts to die. Not that I've ever had that happen.