Jennifer Hudson couldn’t even make it to the top on American Idol -- what could she possibly bring to the big screen? If Dreamgirls is any indication, plenty. Delivering a knockout performance that all but dares the Academy to ignore her for a Best Supporting Actress nomination, Hudson is a revelation in the role of Effie, the lead singer for the R&B outfit the Dreamettes who’s relegated to backup vocals once savvy yet sleazy manager Curtis Taylor Jr. (Jamie Foxx) decides that the noticeably thinner Deena (Beyonce Knowles) would better help the Supremes-like group hit it big (the third member, well-played by Anika Noni Rose, is content to remain in backup mode). On the narrative level, this adaptation of the Broadway smash is only too happy to wallow in its show biz clichés, content to let other ingredients (the music, the acting) carry it along. Yet Lewis is so powerful that the film suffers whenever we’re left with just Beyonce or Foxx. Luckily, Eddie Murphy is on hand providing some prickly tension as fading star James “Early” Thunder, while writer-director Bill Condon stages the musical numbers for maximum impact. But it’s Hudson who owns Dreamgirls; her delivery of “And I Am Telling You I’m Not Going” is worth a standing ovation -- or at least a recount on American Idol -- all by itself.