"Hey You" was released Thursday for MP3 downloads on Microsoft's home page, www.msn.com, said Warner Bros. Records, Madonna's label. The first million downloads of the tune will be free with Microsoft pledging to donate a quarter per download to the Alliance for Climate Protection for the first million downloads.

Madonna is scheduled to perform "Hey You" at Live Earth's London venue, Wembley Stadium. Warner Bros. Records also announced it will release a CD/DVD of the Live Earth Concert Series.

"The early release of 'Hey You' is an incredible boost to our efforts to get people engaged in the environmental cause," said Live Earth and Save Our Selves organizer Kevin Wall. "We are thrilled that Madonna donated her art to Live Earth and is a part of this movement for us."

The Live Earth concerts, organized by former U.S. Vice President Al Gore, are being held simultaneously in seven worldwide locations on July 7 and will be streamed live on MSN.