Don't recall 500GB but there was an opinion piece on Wired or Cnet about a year ago that assumed a compression, storage, and bandwidth were increasing per Moores law. Therefore, at some point in the near future, it would be possible to have the entire world's collection of digital music on your hardrive. The jist of the article was that RIAA was trying to hold the sea back with a broom. I'll dig it up if anyone is interested.