Conan O''Brien ended his brief tenure on the Tonight show with a wide smile and a guitar in his arms.

The red-haired comic joined a band led by blond-wigged comic Will Ferrell with Beck and ZZ Top guitarist Billy Gibbons for a raucous rendition of Lynyrd Skynyrd's Free Bird. O'Brien accepted a $45m deal from NBC to leave the show, $33m of which he will pocket himself. He had been in the job for only seven months.

Despite the rancour that marked his final two weeks, O'Brien emotionally urged his fans not to be cynical and said their support made a sad situation "joyous and inspirational". He even thanked NBC for more than 20 years of employment but mixed in a few final jabs during the show.

Walking away instead of accepting a demotion is the hardest thing he's ever had to do, O'Brien said. "This is the best job in the world," he said.

O'Brien will be replaced on 1 March by the man he took over from: Jay Leno.

Faced with the flop of its prime-time Leno experiment, NBC sought to move him back to 11:35 p.m. and asked O'Brien to move Tonight a half-hour later, past midnight. O'Brien refused, opening buyout negotiations that ended last Thursday, and triggering a remarkable period of late-night comics taking brutal shots at NBC and at each other.

O'Brien told fans last Friday: "I really feel this should be a happy moment. Every comedian dreams of hosting the Tonight show and, for seven months, I got to. I did it my way, with people I love, and I do not regret a second. I've had more good fortune than anyone I know, and if our next gig is doing a show in a 7-Eleven parking lot, we'll find a way to make it fun."

Earlier, he showed a package of clips from his seven-month stint, including the mock run from New York to California used on his first Tonight show. He ended it with a placard saying "To Be Continued."

His future is uncertain. Fox has expressed interest in having him do a late-night show, but the network is checking with its affiliates to see if they would support it. Under his exit deal, O'Brien is free to start another show after Sept. 1. He's not allowed to give interviews or make other television appearances for three months.

Tom Hanks offered to let O'Brien keep hosting the show in Hanks' home, promising he and wife Rita Wilson would try to stay up. Steve Carell did a mock NBC "exit interview" and shredded O'Brien's key card. Neil Young sang "Long May You Run" and thanked O'Brien for supporting new music.

During his monologue, O'Brien tossed around a few ideas about what NBC might do with the studio it constructed for him when he moved to California from New York in the middle of last year.

One suggestion: "Leave the studio cold and empty and rename it `the world's largest metaphor for NBC programming.'"

O'Brien told the audience that "we have exactly one hour to steal every single item in this studio."

As soon as fans had been let in the studio, workers walked around to unscrew and remove signs posted all over that said "Tonight Show with Conan O'Brien: Audience."

Although NBC had sought to keep O'Brien, who hosted the 12:35 a.m., New York-based "Late Night" for 15 years while waiting for his shot at "Tonight," executives said the network was losing money with his show. O'Brien had lost half the audience that Leno had drawn in the time slot, slipping behind CBS' David Letterman in the ratings. O'Brien's managers said he needed more time and blamed some of the ratings troubles on the sinking fortunes of Leno and the local news programs that preceded "Tonight."

Fans waiting to see the final show expressed their support. Three fans from San Diego put up a tent and camped overnight in the rain to get in.

"He's just generally a likable guy," said Lesley Vamous, a fan from Australia. "I think that's why I like him and I watch him. He seems like an approachable guy, and most of the things he does are kind of funny."

Juliet DiFranco of West Toluca Lake, Calif., said she couldn't watch Leno like she did before. "He just seems like such a jerk for not retiring," DiFranco said.

Leno's name never came up during the show.

O'Brien asked his viewers not to be cynical.

"I hate cynicism," he said. "It's my least favorite quality and it doesn't lead anywhere. Nobody in life gets exactly what they thought they were going to get. But if you work really hard and you're kind, amazing things will happen."