Tuesday's American Idol performance episode was a night of extremely premature nostalgia for the year 2000. AI alumna Kimberly Caldwell and Popstars grad Rosanna Tavarez — who cohost TV Guide Channel's Idol Chat — both agree that this week's theme was harder than you'd think. "The big challenge is that, when you have songs [released in] the past five years, people have in pretty recent memory what [the original artist] sounds like singing it," says Tavarez. "It was a bit like karaoke," adds Caldwell. "A lot of the songs they sang in previous weeks, they'd never heard before, so they did their own version. What I found this week was that a lot of them really just copied the original instead of stepping out on a limb." Here's their take on how each of the six finalists handled the challenge.

Carrie Underwood
Rosanna: I think Carrie chose a song that, even though it was a country song, it wasn't the most entertaining song to hear. She did a good job, but she didn't do a great job. However, I loved her hair that way. I was so happy to see she didn't have Dolly Parton hair. She had the country style going, but it was modern and more understated, which totally worked for her. I hope she took a Polaroid.
Kimberly: She looked really cute. I love her hair straight — I do not like it curly. She's definitely getting better at her stage presence. But at the same time, Randy said she was pitchy. Everyone was having pitch problems. Maybe because they were nervous that Clay Aiken was in the audience!

Bo Bice
Rosanna: I wasn't so into it. Gavin DeGraw sings the song so well, it's already challenging to come up with another version of it that's equally as good or better. His stage presence was great. His singing wasn't the best. He was kind of pitchy and flat; he was yelling through some of it. I'm not crazy about the texture of Bo's voice. I'm really into the whole Bohemian look. I could have done without the glasses, but I think it was fitting. There's a way to look stylish and push the envelope without looking goofy.
Kimberly: I hope it doesn't hurt him that he came out about having a girlfriend. Because I know it hurt my feelings. When I was on the show and was dating someone, it came out. After I got kicked off, Randy said that was a reason. People want to look at you and think they could have that fantasy. If you have a girlfriend or boyfriend, that's shot. I personally didn't think he sang that well, but I really don't think it matters. The judges loved him and the crowd went crazy. Randy couldn't even start talking for like five minutes.

Vonzell Solomon
Rosanna: Vonzell has really consistently been doing well in the competition. She was a little off at the beginning, but I think we have a tendency to judge people's performances based on a perfectly produced CD version of the song. These are people who are singing live, so that needs to be taken into consideration. She has incredible and really effortless stage presence. She doesn't get gimmicky. I think when she smiles and winks, she's doing it because she really feels like it. She's not concerned about her performance because she has a voice she can rely on. She really is a triple threat.
Kimberly: I really wish the judges would get ear monitors because, on my side of the TV, I think she sounded good. If they're judging the contest, they shouldn't be saying, "I don't really know how you did. It was loud in here, sorry." It shouldn't be taken lightly; Simon has a huge impact on the audience.

Anthony Fedorov
Rosanna: Anthony surprised me last night. I really think he'd be amazing on Broadway. Sometimes people think that's a rude thing to say — the whole cheese factor comes up. But I think he'd be great. I think Simon said it best; what a brave person he was to choose [a Celine Dion song]. But he did a phenomenal job. His voice is that kind of voice... long, held out notes, very emotional kinds of songs.
Kimberly: I wasn't a big fan of his until this week. He really looked good. He looked the best he's ever looked, he sang the best he's ever sang, and he looked the most comfortable. I think it was his best performance. I don't really enjoy the kind of music that he does, but his audience does.

Constantine Maroulis
Rosanna: Though I have slightly fallen for the pouty-pout thing that he does, and have been slightly attracted to him in the last couple of weeks, I don't think he did a good job last night. His vocals were really off, and I think it was Randy and Simon who agreed it was a performance that was heavy on the stage presence and almost nonexistent in terms of the vocals. He was amazing on stage. A little forced, maybe. The song didn't suit his voice.
Kimberly: I think he does good every week, but I always think he's so overdone. Just like Randy said, I felt like I was watching a karaoke contest. He was like performing for his friends. At the same time, he goes and kicks at the camera and winks. At least he's having a good time. That's what's cool about him.

Scott Savol
Rosanna: Oh, Scott, Scott, Scott. Singing is about storytelling by using your voice. And when you tell a story, there is a cadence in your voice in order to engage people. Scott doesn't get that. I think maybe he gets a little intimidated or scared and he shuts down, especially in the beginning, [and] maybe grows a bit more comfortable by the middle or end. It's like watching someone lazily tell a story. He's lethargic on stage. I think that if he trusted his voice more, he could sound better, he could engage us as an audience — but he fails to do that because he doesn't work at it. He just sits there.
Kimberly: He looked really nice and cleaned up. The thing with Scott is that nothing is ever outstanding. Nothing is ever amazing. He should have come out there, let loose, given it his all, sang a song that showcased his vocals. This was the week he really needed to be on. His appeal is that he has a very pure voice. People who aren't from L.A. like pure, simple things. He gave the least engaging performance.

This week's favorites to win?
Rosanna: I think the winner should be Vonzell. I have a feeling it could be Carrie. She's got that whole country girl thing going on, even down to the farm, for crying out loud.
Kimberly: I don't know this week. I really think Anthony did a good job. I don't know if he was my favorite this week, but I think he was the best. After Scott's gone, it's going to be a battle.

Idol Chat airs Thursdays at 8 pm/ET on TV Guide Channel.