Carrie Underwood revisits the show that made her a star tonight, as she performs on 'American Idol's' charity special, 'Idol Gives Back.' The country superstar will cover George Michael's 'Praying for Time' on the show, and will also reportedly take the stage with 'Desperate Housewives' star Terri Hatcher while the actress attempts to cover Underwood's 'Before He Cheats.'

Underwood, the most successful 'Idol' alum to date, says she loves being a mentor to the show's current contestants.

"I always try to talk to them, and mainly what I say is, 'Don't take anything for granted.' For some reason, it can get to where people play the game a little too much and forget why they're in it. It's because they love music and because this is what they've always wanted to do," she says. "But don't burn bridges. It's such a small industry that every single person you meet you're gonna see later on. I think a lot of people forget that too."

Tonight's star-studded 'Idol Gives Back' includes appearances by Robin Williams, Brad Pitt, Reese Witherspoon, Miley Cyrus, Annie Lennox and a host of other big stars from movies, TV, sports and music. The show aims to raise millions of dollars for various charities that aid underprivileged children. It airs at 7:30pm ET tonight on FOX.