It wasn't so long ago that Russian opera, beyond a few acknowledged masterpieces by Tchaikovsky and Mussorgsky, was virtually an unknown quantity in the wider world of music. If the conductor Valery Gergiev has played a huge role in changing that, a glamorous star soprano like Anna Netrebko can potentially do even more -- and her Russian Album ought to make more than a few new converts to the cause. Partnering here with Gergiev and the orchestra of St. Petersburg's Mariinsky Theatre, Netrebko has put together a program of entrancing arias and songs by five of Russia's greatest composers. With only one well-known selection, the "Letter Scene" from Tchaikovsky's Eugene Onegin, it's also a rather daring program: Netrebko asks us to follow her into unfamiliar territory, but it's a journey that few listeners could refuse. The unfettered lyricism of Rimsky-Korsakov's operas gets special attention, with scenes from The Snow Maiden, The Tsar's Bride, and The Tale of Tsar Saltan, allowing Netrebko's voice to soar radiantly over the Mariinsky orchestra. She also looks back to the origins of Russian opera with Glinka's A Life for the Tsar and forward to the 20th century with Prokofiev's War and Peace -- from which the role of Natasha has counted among her most important successes on stage. But it may be the Romantic melancholy of Rachmaninoff that suits Netrebko's voice most fully, both in a scene from his seldom-heard opera Francesca da Rimini and in orchestral versions of two haunting songs. As for Tchaikovsky's famous "Letter Scene," Netrebko sustains an intensity of emotion that more than measures up to the beauty of her singing, making it a perfect capstone to this exploration -- with luck, just the first of many -- of her nation's uniquely splendid music.