Live Earth events drew more than 10 million online viewers Saturday, the most ever to simultaneously watch a concert broadcast over the Internet, according to Microsoft.

Madonna performing at the Live Earth concert in London. Photo courtesy of LiveEarth.org

The concerts were beamed live from venues in or near New York, London, Hamburg, and several other major cities around the world over Microsoft's MSN network. As of 3 p.m. Saturday, MSN had delivered more than 10 million video streams, the company said.

"The over 10 million streams MSN has delivered so far today represent a milestone in live Internet broadcasting," said Joanne Bradford, VP and chief media officer at Microsoft's MSN unit, in a statement.

Live Earth featured dozens of musical acts -- from Madonna to Metallica -- playing from multiple venues over a 24-hour period on July 7. The concerts were aimed at raising awareness about global warming -- a theory that claims the earth's temperature is gradually rising due to man-made influences.

The combined concerts were expected to draw a total live audience of more than 2 billion people.

In addition to the live Webcast, Microsoft has also made archived footage of the events available on LiveEarth.MSN.com. As of Sunday, however, some users were having trouble viewing the clips -- an indication that Microsoft's servers may be overwhelmed.

One user on the MSN Live Earth site complained in an online forum that the rebroadcast is "nothing but a bunch of herky jerky stop frames."

It's not uncommon for live Internet broadcasts of high-profile events to experience performance trouble. A 1999 Webcast of the Victoria's Secret fashion show in New York City famously crashed, leaving millions of viewers frustrated.