Now that Circuit City is gone, Best Buy has another target for dominance in the consumer-electronics space. Except this time it's Wal-Mart.A new Best Buy ad campaign features a customer calling one of its stores about details on a television. The person is calling from a Wal-Mart. Says the Best Buy representative on the phone: "You're obviously calling us because we're knowledgeable. We've got the price match guarantee, so why don't you come on in?" Youch! So we take it the message is that it's tough to get good service in the electronics section of a Wal-Mart?These ads are launching at a time when Best Buy is cutting its marketing budget and profits and same-store sales are down at the chain. Can the company convince a budget-weary consumer not spending as much on big-ticket items that it can get the same deal there as Wal-Mart?