At the start of its fifth year, our favorite local museum of the moving image has made a few concessions to modernity, installing new seats and a booming Dolby system to make its repertoire of classics, cult movies, and recent raves feel and sound even better. But the theater's distinguishing characteristic remains its programming--which, among the ever-more-endangered species of American rep houses, is the strongest this side of the Brattle in Harvard Square. Oak Street's quarterly schedules represent a delicate balancing act between populism and esoterica, resulting in a healthy mix of high and low from here and there. Where else could you screen Swingers one night and Tarkovsky's Stalker the next? Or a double feature of films by the Iranian auteur Mohsen Makhmalbaf, followed by a weeklong run of a newly struck print of North by Northwest? That Oak Street snared the regional premiere engagement of Hou Hsiao-hsien's world cinema cause célèbre Flowers of Shanghai bodes well for its bid to increase the ratio of new films to old. In the meantime, on a night when the theater is screening a vintage gem like the New Wave gangster flick Le Doulos, one has the rare feeling of being among the luckiest movie lovers around.