A decade ago, only one word was needed to sell a dance concert: Baryshnikov. Today, mention that Baryshnikov will perform as a member of the White Oak Dance Project and you hear: "Baryshnikov? Isn't he old?" Yes, but his dance is perhaps better now than ever. The amazing leaps of his classical ballet days are gone, of course, replaced by the more human vocabulary of modern dance, but in Twyla Tharp's solo for him, Pergolesi, his movement seems richer, deeper in meaning--and every gesture is exquisite. His name still sells tickets, but Baryshnikov's White Oak project is about as far as you can get from a mere star vehicle. Founded in 1990 by Baryshnikov and choreographer Mark Morris, it's devoted to exploring a thoroughly modern repertoire by a wide range of choreographers: featured on these two programs are Tharp (whose 1976 Push Comes to Shove gave Misha his first taste of contemporary dance), Merce Cunningham, Jerome Robbins, Hanya Holm, Kevin O'Day, and of course Morris. The nine White Oak members, who hail from the world's top companies, are amazingly mature for dancers: all are over 30. There's an understanding in the art that dancers should not perform past their "prime," but White Oak Dance Project offers a new perspective on that dogma, proving that--even in dance--artistry often deepens with age. Thursday at 7; next Friday and Saturday, July 15 and 16, at 8; and next Sunday, July 17, at 3 at the Auditorium Theatre, 50 E. Congress; $15-$55. Call 902-1500 for tickets and info.