Claims to have no fans. Maybe from across the room, you won't hear the hard drive(s).
Or if you can afford this, you could probably replace with SSD.
Doesn't seem to be available for sale yet:
http://www.lumenlab.com/
http://speedingcomputer.com/2007/10/thi ... y-is-a-pc/
Interesting idea, anyway. At the right price, and with HDMI bypass of the computer allowed, I might be interested.