You might also consider
Magnatune. They are kind of like a new record label that offers their artist's music in a variety of digital formats (including lossless). Hopefully we will see more labels like this in the future.
Another possible source that sounds very promising is
MusicGiants. They plan to offer high resolution multichannel audio this fall. Maybe they will provide an alternative to DVD-Audio and SACD that can easily be played from our PCs.