I doubt this will work with tunes bought at the store. THe DRM is still in the files even if they are streamed, so
a) you will have to have iTunes
b) you will have to make your work computer one of the 3 computers that work with your tunes.
edit: it actually only supports MP3 so that rules out iTMS songs completely (they AAC). I don't see why not though, Surely you can stream an unprotected AAC through a web site just as easily as any audio format no? And isn't this software just a simple webserver with a database created from the iTunes library?