What does Julia Roberts sing in stepmom the car scene with kids?

Julia Roberts' character, Isabel, doesn't actually sing in the car scene with the kids in the movie "Stepmom."

She does, however, play a cassette tape of the song "You've Got a Friend in Me" from the movie "Toy Story" in order to cheer up the kids, Anna and Ben, after their father leaves them with Isabel for the first time.