LAS VEGAS -- The reigning NBA champions are about to lose their glue guy.

James Posey, arguably the most coveted unrestricted free agent left on the market, agreed to a four-year deal with the New Orleans Hornets on Wednesday worth an estimated $25 million, his agent, Mark Bartelstein, said.

"It was a really tough decision for him," Bartelstein said. "Boston was an incredible experience for him every way you look at it. If he was going to leave Boston, he wanted to make sure it was for a team that would compete for championship immediately and the Hornets certainly are in that world."

Because of future luxury-tax concerns, Boston was apparently reluctant to offer Posey, 31, more than a two- or three-year deal starting at the league's mid-level exception (just under $5.6 million) in spite of Posey's considerable contributions to the Celtics' first championship since 1986.

Getting Posey would be a huge coup for the Hornets, who are coming off a breakthrough season and increasingly billed as a future power in the West with quality starters such as David West, Tyson Chandler and Peja Stojakovic surrounding face of the franchise Chris Paul.

But the Hornets went into the summer desperate to fortify their thin bench and import a proven winner like Posey, who has won two rings in the past three seasons with the Celtics and Miami Heat.

Shortly before the draft, the Hornets traded away their only draft choice, the 27th overall pick, to the Portland Trail Blazers in exchange for $3 million in cash with the stated purpose of using that money toward a proven player in free agency who could help them win right away.

With the money they received from Portland, combined with the savings that came from not having to shell out guaranteed money to a first-round draft pick, the Hornets were able to offer a generous enough deal to bring Posey to New Orleans.