Tom's Hardware Guide Mobile Devices: Mobile Storage: Your Entire CD Collection In Your Pants Pocket - 40 Audio CDs On Your Key Ring, Or A Whopping 400 In Your Vest Pocket: "The contents of 40 CDs encoded in very good MP3 quality fit easily on a four Gigabyte Microdrive, which Archos has bundled with a USB 2.0 interface and a fold-out USB port in a miniature case. Archos, with disarming modesty, calls this the Arcdisk 4 GB HD USB Key. Weighing in at less than an ounce and a half, the Arcdisk 4 GB fits handily on any key ring. "