When "The Tonight Show with Conan O'Brien" premieres on June 1, the show will have a whole new look as well as a new host, but it will still have a sense of humor.

At least it will if O'Brien has anything to do with it -- which he does. "Television is changing rapidly, and I want to make sure [the new 'Tonight Show'] isn't too buttoned up," O'Brien told reporters at the NBC Television Critics Association junket at the Universal Hilton. "I want to make sure it is funny and a worthy 'Tonight Show.'"

That said, O'Brien is very much aware of the all the buzz about the changing of the guard, especially since NBC announced its plans for Jay Leno to have a one-hour nightly series at 10 p.m.

"I think there has been speculation and uneasiness every time there has been a change in 'The Tonight Show' host," he explains. "If you look back at the history of the show -- changing from Jack Paar to Johnny Carson to Jay Leno -- people inherently don't love change. Jay has been hosting the show for 16 or 17 years now. This is a big change.

O'Brien will sign off as host of "Late Night" on Feb. 20, and beginning March 2, "Saturday Night Live" alum Jimmy Fallon will replace him.

So what does O'Brien foresee for that Feb. 20 show?

"For my last show, I don't want to do a big salute to me. I am departing for a brief period of time and then reappearing in this fantastic dream job, so I want to walk the line carefully," he says. "I want to make sure I don't let down [hardcore fans], but I want it to look like me."

As for going head-to-head with David Letterman, O'Brien says, "I don't think I can touch David Letterman's legacy in this business. I will always be in awe of that man. If I cure cancer on my first show, I still won't [touch his legacy]. I feel the people who watch Dave and love Dave, I am not going to change their minds. I just want to do the show that I do. "