A hard drive, whether it's one that you can yank out of your machine or one on a network, is probably the best and most reliable backup device you can use. It sure beats the hell out of a tape or Zip drive for reliability. Seagate just let us know about an external hard drive that you can plug into a USB port, which sounds to us like a great idea for moveable, removable storage. The company's new USB DiskStor, available in 20- and 40 GByte capacities, allows you to grab your backup and plug it into your laptop or your neighbor's machine if you cook your system (or if you just want to transfer files). If you live in Europe or in Asia Pacific regions, you'll have to fork out extra cash to get one with an appropriate power supply. In the U.S., the drives cost $269 for a 20 GB DiskStor 20 and $349 for a 40 GB DiskStor 40. The drives, which Seagate says provide a data transfer rate up to 12 Mbits/sec, come preformatted for compatibility with Windows 98, 2000 Pro and Millennium.