Numerous data recovery tools exist.
GetDataBack for NTFS http://runtime.org
You need a new external/internal hdd all recovery tools want a new hard drive to put their files on during the recovery process.
Run one of the many recovery tools and see what it can see.
As @Hennes mentions if you here strange clicking sounds you could have a head crash or worse.
If you can manage to open the external hard drive and attach it to a SATA or IDE port things will go much faster. USB is limited to approx 30mb/s and SATA can go higher than your hard drive. However you should get at least 2x-3x faster than USB 2.
Also if the data is really important a service like DriveSavers.com will gladly charge you as much as $1000-$2000 to get it back.