miniKeys 

Places a virtual piano on your screen that can be controlled with your keyboard, mouse or both. Comes with high-quality piano sounds recorded at 16-bits and 22,050 Hz.

miniKeys is a virtual piano for Windows that comes with its own high-quality piano sounds. Although miniKeys is quite responsive, its performance can suffer if too many applications are open at the same time. Its performance may also be compromised on processors slower than 400mz. The sounds were recorded at 16 bits, 22,050Hz.