Best Buy Co Inc plans to buy digital music service Napster Inc for $121 million in cash in an effort to compete with Apple's dominant iTunes service and its iPod music players.

Best Buy, one of the largest retailers of CDs, and Napster, once the best known name in digital music, both offer digital subscription services, but neither have mounted much of a challenge to Apple, which holds more than 70 percent of the US digital music market.

Napster and Best Buy are betting they have a better chance by combining rather than competing with each other.