"American Idol" winner Kris Allen and fourth-place finalist Allison Iraheta will perform on "Billboard's New Year's Eve Live." ET chatted with the two about their upcoming performances and what they think "American Idol" will be like without Paula Abdul -- and possibly Simon Cowell.

"Obviously, we're all going to miss her," Allison says of Paula's departure. "I honestly have to say that I'm pretty happy that we got the chance to work with her. Sorry season nine! But, they're getting Ellen [DeGeneres], so we'll see how that goes. I really want to see what she has to bring to the table."

Kris adds that Paula is a sweetheart, saying, "I think the show will definitely miss her. Obviously, people tuned in to watch what Paula was going to do. But she was just a nice person to have on there, but Ellen's going to be ... I don't know of one person that doesn't like Ellen."

As for the rumors that Simon Cowell may depart after the upcoming season, Allison and Kris say they can't imagine the impact on the show if it loses two of the three original judges.

"Obviously, Simon's a big watching point for a lot of people and they would have to replace him, but I really don't have a clue," Kris attempts.

What they do know is why they want to be in Las Vegas on New Year's Eve performing on the Billboard show.

"Who wouldn't want to be in Vegas performing? I mean, it's pretty much an experience of a lifetime for me and for both of us. It's going to be a lot of fun," Allison says.

For Kris, it will be a first. He has never actually been to Las Vegas -- except for a change of planes at the airport. But it will be a bit different for him, because he has never performed on New Year's Eve before.

"Last year, we had a party at my house and we had this small deck on the roof," he recalls. "There were like 45 people at my house, or something like that. I don't know the number. We all had sparklers, and somebody's pants caught on fire. So, that was pretty scary."

And with New Year's just around the corner, the two weigh in on their resolutions for 2010.

"For me, its just work harder on music stuff, just writing and performing and all that. So, that's my resolution," Kris says.

"Wow. You're going to make my resolution sound like crap. I didn't have a New Year's resolution. My New Year's resolution was to not have a New Year's resolution," Allison admits.

"Billboard's New Year's Eve Live" will air New Year's Eve Thursday, December 31st from 11 p.m. until 12:30 a.m. live on the East Coast on FOX. It will be tape delayed in other time zones.