NEW YORK (AP) -- Shock jock Howard Stern, surrounded by strippers and cheered by thousands of fans, began promoting his switch to satellite radio Thursday at a Manhattan rally where he handed out free boom boxes and satellite subscriptions.

"Down with the FCC!" Stern told a legion of sign-waving backers gathered at Union Square. "They have ruined commercial broadcasting."

The fans agreed, screaming "Howard rules!" as their hero addressed the overflow crowd. Stern supporters spilled into the streets surrounding Union Square, stopping noontime traffic throughout the neighborhood.

"Most people think it, but don't say it," said Stern fan Peter Frankel, 50, president of a Long Island janitorial company, as he walked off with a free Sirius boom box. "Howard Stern says it. It's healthy for society."

Across the square on Fifth Avenue, the culture war took on another slant, with fans of the rival satellite radio XM staging their own rally, hoisting placards touting the shock jock antics of its "Opie & Anthony" radio team.

Stern will be able to say anything he wants once he starts at Sirius Satellite Radio, which is free of Federal Communications Commission restrictions. Stern has battled for years with the FCC over the content of his salacious show.

Last month, Stern announced he was leaving traditional radio for Sirius -- even though his current syndicated show is scheduled to run through December 2005.

Stern has hinted on his morning program that his January 2006 start date at Sirius could be pushed up. His current employer, Infinity Broadcasting, has ordered Stern to cut back on his on-air references to his move.

Stern, who was scheduled to appear later on "Late Show with David Letterman," left no doubt about his allegiance at the event.

"Once you start listening to (satellite), it's like crack," Stern said to cheers. "You will be addicted."

Stern personally handed out a free Sirius boom box to the first 500 fans, while he had another 20,000 redeemable certificates for free radios. The equipment allows listeners, for $12.95 a month, to receive 120 channels of commercial-free music, sports, news, talk, entertainment and traffic.

The certificates must be redeemed online by Nov. 24, and the redeemers must sign on for a year of Sirius -- which would leave them just short of Stern's January 2006 debut. In October, Stern signed a five-year deal with the satellite company worth an estimated $500 million.