I have a QNAP TS-109 Pro. Love it, but wish the processor was a bit faster. Quiet, feature rich, firmware updated every few weeks, well supported.

Just installed the new (v7) SqueezeCenter on it, and am using it to serve a Logitech Duet, which is really good.

For the QNAP, see here: http://www.qnap.com/pro_detail_feature.asp?p_id=79

For the Duet, see here: http://www.flickr.com/photos/jonbauer/2201090662/ (video too).

- Jon