Instructions
Turn the Xbox 360 off. Disconnect all accessories.
Press the small, oval release button on the hard drive. Lift the hard drive away from the hard drive bay. The hard drive is located on the top of your Xbox 360 if the console is standing up, or on the left side of the console if the console is laying flat.
Remove the new hard drive from its package. Press the back of the hard drive against the hard drive bay, with the silver nameplate facing up. Press the front end of the hard down until it clicks and locks into place.
Reconnect all accessories and turn your Xbox 360 back on. Sign into your Xbox 360 account and click the "System" menu. Select "Memory." Ensure that your new hard drive is part of the memory options. If your hard drive is 120GB, for example, it should read "120GB Hard Drive."