This review takes a look at an adapter made by Creative that allows users to stream music from computers to a stereo: The reviewer's biggest complaints surround user interfaces. The remote is apparently clunky and doesn't offer certain features like the ability to make song lists or rewind or fast forward. Also, he says the PC software isn't very user friendly.
He also complains about the lag between the time when you choose a song and when it starts playing. I suspect that happens because it takes a few seconds for the box to query the computer and grab the song to start playing it. That ought to speed up in future versions of these products.