Sony created the portable audio market in 1979 when it launched the Walkman brand. Then Sony beat Apple to market in digital music by two years -- but its first products bombed. The company's biggest misstep was its reliance on ATRAC, a proprietary file format used with Sony's MiniDisc. After 2000, digital music was all about file-sharing, and it was all MP3. Couple that mismatch with confusion within Sony -- its VAIO PC division brought out products (including the MusicClip) that competed with Walkman digital players -- and Sony set itself up for a stumble.