As Bob Marley is to reggae and Elvis Presley is to rock & roll, so Hank Williams is to country: the big gun, the patron saint, the standard-bearer against which all others must forever be measured. This tribute, hosted by Hank Williams Jr. and staged at the Grand Ole Opry (from which Williams had been banned for drunkenness at the time of his death at age 29 in 1953), intercuts dramatizations of Williams life with a concert in which a variety of country stars, including Kris Kristofferson and Johnny Cash, sing his songs. And what songs! ''Hey, Good Lookin','' ''Your Cheatin' Heart,'' ''Lovesick Blues,'' ''You're Gonna Change'' -- the guy left one hell of a legacy. Perhaps most affecting is seeing a trim, raven-haired Cash deliver a mournful reading of an obscure gem called ''Men With Broken Hearts,'' which recent events render all the more poignant.