Providing further evidence that the digital medium has overtaken physical CDs, an independent study found that iTunes passed Wal-Mart in music sales during the months of January and February, making Apple’s service the largest music provider in the U.S. It was the first time in iTunes history that they topped the sales charts. The study was announced the same day iTunes learned they’d have to compete against a new MySpace music service, which may effect numbers in the coming months. The impending new albums from Madonna, Mariah Carey and other marquee acts could shift the scales back to the physical product over the coming months.