According to Reuters, Kim went into his local Best Buy and made a purchase using his debit card. Along with Kim's purchases, the checkout clerk scanned an MSN free trial disk. Kim says that he questioned why the disk was scanned and was told it was for stock-keeping purposes. He thought nothing more of it... For a while.
Some time afterwards he discovered that money was being debited from his bank account. It was going to MSN. Best Buy had passed Kim's debit card details to the Microsoft division and it had activated an account for him.