"They Went Thataway," American Film Institute, Kenny Center. $3 non-members, $1.50 memebers. Box office open daily noon to 4 p.m. and 5:15 to 9 p.m. 785-4600.

If you are old enough to know that Roy Rogers was not always a hamburger stand, you will know that Westerns aren't what they used to be, for better or worse. That is the subject of the American Film Institute series this month, "They Went Thataway," a series of thirty-five old westerns featuring stars like Hopalong Cassidy and Tom Mix, Gene Autry and Randolph Scott, even the western forays of Marlene Dietrich and Judy Garland. And Trigger, of course. The AFI is leading into the series today with a sale of vintage Western posters ($5 to $10), and a lecture which is undoubtedly already filled. Then tomorrow at 8:30 p.m. they are showing John Ford's "Wagonmaster" with "Directed by John Ford." April 8 at 9 p.m. will be "The Spoilers" with John Wayne and Marlene Dietrich plus "River of No Return" with Marilyn Monroe. The first week concludes with Judy Garland and Angela Lansbury in a kind of westernized version of the health food movement, "The Harvey Girls," April 9 at 6:30 p.m. and April 10 at 9 p.m.