Watch Vince Gill and Amy Grant this Sunday on the PBS special, "A Capitol Fourth 2004." Vince and Amy are two of the musical headliners who'll take part in the patriotic celebration, broadcast live on the west lawn of the U.S. Capitol. The show airs 8 to 9:30 p.m. Eastern. Vince will serenade the audience of more than half a million people during a tribute to Ray Charles, singing the classic "I Can't Stop Loving You." The happy couple are also scheduled to make guest appearances on the Fox Network's "Fox & Friends" the morning of July 3, as well as CBS's "Early Show."