All of the music on download.com must be submitted with authorization from the artist(s) before it's offered on the site. So, as far as Cnet could ascertain, all of the music is completely legal. If an artist did not give permission, he/she can notify Cnet and have the song(s) withdrawn and the matter looked into. (I believe they keep records/documentation of who submitted what.)

I too have seen songs from well-known artists, including Garth Brooks, available from download.com, but was only mildly surprised. Artists frequently offer individual songs for free, sometimes only for short times, usually for self-promotion or a general appeal to their listeners. For a couple of weeks the BBC offered several Beethoven compositions for free download from their site, with the stipulation that the downloader could not distribute or reproduce it. The offer was part of a 'tribute' to classical music. Thus, while most of such offers are fraudulent, occasionally you'll find a genuine steal from a reputable source, such as Cnet.

Regards,
John