Carlos Santana proved unbeatable at last night's 42nd Annual Grammy Awards at the Staples Center in Los Angeles. The veteran guitarist from the '70s won in every category for which he was nominated, including the night's top honors: album of the year ("Supernatural"), record of the year (to his single with singer Rob Thomas, "Smooth") and song of the year ("Smooth" again). In all, Santana himself collected eight awards, matching Michael Jackson's 1983 record for the most Grammys won in a single year. (The song of the year trophy went to the songwriters of "Smooth," Itaal Shur and Rob Thomas.) Santana, 52, told reporters backstage that tying with Jackson was "a real honor." He also said that he was proud "to be able to demonstrate to the people that deepness and class can be as profitable as shallowness and crass." Ricky Martin, Marc Anthony, the Backstreet Boys and Britney Spears (who lost the best new artist title to Christina Aguilera), despite their high profiles, were left empty-handed last night. Still, the No. 1 topic on early a.m. TV and radio shows today was presenter Jennifer Lopez's dress. Or lack of it. Lopez's outfit, a green and yellow silk chiffon Donatella Versace scarf dress, was cut all the way down to her navel, then split apart again and fell to the floor. (Only a brooch kept the actress-singer from exposing her privates.) As her co-presenter David Duchovny said at the podium, "For the first time in my career I can be sure nobody's looking at me."