"On two occasions, I have been asked [by members of Parliament], 'Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?' I am not able to rightly apprehend the kind of confusion of ideas that could provoke such a question." ~ Charles Babbage (1791-1871)
I've seen it before, and yeah it is cool, but a lot of the notes were off. That's probably because it was a live performance. Anyway, there's also another fantastic Mario theme done a cappella by <a href="http://www-scf.usc.edu/~osmosis/music.html">Reverse Osmosis</a>. Scroll down to the song named "Nintendapella" and clink to listen to the demo.