In July 2006 I bought an external hard drive. It had a 160 Gigabyte capacity and required external power. It had been acting badly and throwing error messages over the past few months, so I ordered a new external drive, which arrived last week. It has a 640 GB capacity and draws all the power it needs from the USB port. It's a fraction of the size and weight of the old one.
I really shouldn't be surprised, but looking at the two of them side-by-side, it still amazes me how technology continues to advance.