Jennifer Lopez and Marc Anthony

Even the busiest A-listers can spare at least "One Day" for a good cause.

The couple join Sean Paul, Chris Brown, Eve, Bone Thugs-N-Harmony, Cassidy, Floetry, Lyfe Jennings and Mario in what certainly sounds like what will be an R&B and hip-hop-influenced project. The International Peace Concert, celebrating the U.N.'s 25-year-old initiative, will be televised live from Rome on Dec. 9.

"Since each of the Grammy-winning artists who have signed on to sing 'One Day' represent a different type of music--from R&B to pop to Latin pop, to hip-hop, rap, reggae and funk--this song will relate to everyone and show that peace has no boundaries," Garson Entertainment President Rick Garson said in a statement.

In the meantime, Lopez and Anthony are off in Toronto enjoying the fruits of their latest labor of love, the musical biopic El Cantante, about Puerto Rican salsa legend Hector Lavoe. Not only did the film allow the duo the chance to spend gobs of time together, but playing the roles of an explosive husband and wife who undergo major emotional trauma helped Anthony and Lopez, who attribute their successful partnership to "just simple love," appreciate each other even more.

"I realized for the first time how sane we are as a couple--really," Anthony said Wednesday during a festival press conference.

"As crazy as we are," Lopez interjected.

"We'd do these scenes and I'd go home and say, 'We're normal,'" Anthony continued. Then Lopez added: "And I was like, if they could do this for 20 years, surely we can make it through the next weekend."

Lavoe's wife, Puchi, whom Lopez referred to as a "ballbuster," stood by her man during the highest of highs--international superstardom, cultural transcendence--and the lowest of lows--infidelity, his violent temper. The singer, a longtime drug addict, died of AIDS in 1993 when he was 46.

And as far as Anthony's concerned, at least, J.Lo dug into the role of Puchi with a vengeance.

"I've been in the business 27 years, and I've never met anybody with such laser focus and clarity," the singer-actor said. "I'm more laid-back, Hectorian, and it's just fascinating to me. She does not do anything halfway. That's really a virtue, I think. She's just as passionate in her meetings about perfume. I've never seen anything like it."

Anthony had a chance to meet Lavoe before his death and attended his funeral--along with thousands of others.

"His music was like the soundtrack of my life," Anthony, who performed all of his own vocals in El Cantante, said. "He'd said, 'Don't cry when I die, I want to hear a celebration.' And you'd have had to have seen the people singing and dancing on the street, doing exactly what he asked them to.

"I had just put out my first salsa album [Otra Nota] six months before and it was doing very well. And when I walked out of his funeral, people started yelling, 'It's you now! You're the next Hector.' It was the scariest moment of my life. It's scary and so powerful when people anoint you."

But, if his number-one fan is to be believed, Anthony is shouldering his responsibility perfectly well.

"I always knew Marc was a fantastic actor," Lopez said about her hubby, who also appeared in Man on Fire and Bringing Out the Dead. "Nobody could sing like that with all that passion and all that feeling [and not be]."

J.Lo also served as a producer on the Leon Ichaso-directed El Cantante. The project was on her to-do list for five years, ever since receiving a copy of the script, which had been co-developed by Puchi Lavoe. "When you're an actor, you just kind of do your work and you leave it to everybody else," she told Reuters Tuesday. "But when you produce it and it's your baby, and you've been working on it for five years, so you have a little more at stake."

Lopez will be back in Los Angeles next month, where she's expected to present Johnny Depp with Children's Hospital L.A.'s Courage to Care Award at the second annual Noche de Ninos gala Oct. 7. The 37-year-old actress was honored in 2004 for her contributions at a celebration that raised more than $2 million for the hospital.