You can name a band anything you want, of course; but the last group of jazz singers to use a name out of the legal directory was Lambert, Hendricks & Ross, and I've got to think the similarity is intentional. In any case, Sharon Montgomery, Rebecca Plant, and Billy Stritch (who also plays a lot of piano) have themselves one solid and versatile trio: they jam a little, scat a little, and manage to make those three-part harmonies sound surprisingly fat. In years to come, they might carve a place in the jazz-vocal history, but their appeal is not restricted to wiggy aficionados: in addition to Basie's loping "Shiny Stockings" and a gorgeous ballad from the Woody Herman book, their set includes a Patsy Cline torcher and reaches some sort of peak with a 29-song Irving Berlin medley. It's all done up with the kind of bright musical sophistication and Broadway energy you'd naturally expect from a clever New York cabaret trio--which makes the fact they're still based in their native Houston all the more surprising. Tonight through Sunday, Moulin Rouge, Fairmont Hotel, Illinois Center, 200 N. Columbus; 565-7440.