There are two reliable systems I am familiar with both are costly though.
The first is a pc based system that is pretty cool allows you to add modular storage.
http://www.niveusmedia.com/
The second is extremely costly. A large portion of the purchase price goes into a slush fund to cover license costs to avoid the issue of copy right infringement.
http://www.kaleidascape.com/
Check em out. If nothing else they are something to model a home made htpc around.