It looks like all models of HP HDX 16 notebooks use the same fingerprint reader. Here are links to try. The driver is unified (works for both 32 and 64-bit Vista/7), so it should work for you. There's two parts, one is the driver for the hardware, and the second is the software to set it up and use the reader.
Driver:Validity Fingerprint Sensor Driver
Security Software:Digital Persona Fingerprint Reader Software
Post back if you get it working so others with the same problem will get help if they stumble upon this thread.