The rear edge of the HDD (the edge close to the blue "WD Scorpio Blue" label) has three connectors on it. At the far right is one with four pins - ignore that one. To the left of that are two connectors that look like plastic ridges with little right-angle bends on one end of each. These two are different widths. If you look closely at the bottom surface of these ridges, you'll see they hold brass contact strips on them. These two are standard SATA connectors - wide one for power, narrow one for data. Any external case OR any simpler adapter for USB use will have mating connectors built into them so that you can just plug the drive into the adapter. A USB-to-SATA adapter ought to come also with a power supply module that connects to the adapter from a wall outlet. This is because most USB2 ports cannot supply enough power to run a HDD, so power from a better source is needed to ensure good HDD function when using this adapter.