The deal is said to be worth about $40 million over five years.
Williams, who was taken by the Hawks with the No. 2 pick in the 2005 draft, averaged 13.9 points and 6.3 rebounds per game last season.
BOBCATS: The joke began circulating minutes after Michael Jordan hired Larry Brown : The demanding Hall of Fame coach will want to trade everybody on the Charlotte roster before opening night.
A little over a year later, Brown is more than halfway there.
Emeka Okafor became the latest ex-Bobcat under Brown -- joining a growing list that includes Jason Richardson, Adam Morrison, Sean May, Jared Dudley and Matt Carroll . Tyson Chandler, acquired from New Orleans on Tuesday for Okafor, becomes the 27th player to dot Charlotte's roster since the start of last season.
It's uncertain if the moves will be enough to make the Bobcats a playoff team in the improved Eastern Conference. But while Jordan and general manager Rod Higgins sign off on personnel moves, clearly Brown has been given plenty of power.
CAVALIERS: Waived reserve guard Tarence Kinsey , a former University of South Carolina standout.
Kinsey made three starts last season for the Cavs and appeared in 50 games, averaging 2 points and 5.5 minutes per game. He played in nine playoff games.
After the season, Kinsey was charged with drunken driving in Tampa, Fla. He joined the Cavs as a free agent last August.
HORNETS: Signed forward Ike Diogu to a free-agent deal, hoping he can provide solid backup minutes behind All-Star David West .
Diogu, who is 6-foot-9, played in 29 games last season for Portland and Sacramento. The four-year NBA veteran averaged 4.1 points.