Want to put your entire digital music collection on a huge-capacity device smaller than a paperback novel? Look into Creative Labs's Nomad Jukebox 3 and Sonicblue Inc.1's Rio Riot. Each packs a 20GB, notebook-style hard drive; delivers rich, powerful sound; is mobile; and sells for $999.

Despite being a little bulky for most pockets, the Rio Riot emphasizes portability: Its hourglass figure is easy to grip. The larger Nomad is shaped like a traditional CD player and is difficult to grab without accidentally pressing one of its dozen buttons.

You hook either player to a PC via a USB 1.1 port; the Nomad also includes a much faster IEEE 1394 interface. Both players let you navigate through menu options and copious music lists via handy scroll wheels. And both play MP3 and Windows Media Audio files. The Nomad also plays WAV files and has a combination line-in/optical-in port that allows you to encode all three formats without a PC connection. Only the Rio Riot, however, allows you to manually adjust equalizer levels. Accompanying both shipping units are rechargeable lithium ion batteries and an adequate set of headphones.

Although the players were handy, both had glitches. I was able to fix the Nomad's repeated crashes by resetting it or by removing and reinstalling its battery. The Rio Riot suffered from similar -- though less frequent -- lockups, which resetting solved.

Choose the Rio Riot to have lots of music on the go. But if you want a stereo component that's truly mobile, I'd recommend the Nomad Jukebox 3 for its additional features.