There is always a question from commoners whether to choose USB or external Serial AT Attachment (eSATA). Most home users should not worry too much about eSATA. This technology based on the SATA cables that connect internal hard drives, transfers data much faster than USB 2.0 and Firewire connections. But few computers include eSATA ports. For example, Dell and HP only offer them on a handful of desktops and laptops; Apple doesn’t provide them on Macs. Most hard drives, in turn, only support USB and Firewire. If you will move large files back and forth and plan to buy a higher-end desktop or laptop in the next year or so, an eSATA-compatible drive could be a good investment.

Otherwise, stick with USB or Firewire. The latter connection is especially useful on most Macs, where it keeps too scarce USB port open. Another tip is getting a “bus-powered” drive, which will run off your computer’s power supply and won’t need its own wall outlet.