Linda Lacetti celebrated her 29th birthday, kissed her children goodby and left Fremont with three other adults and two children for a vacation in Palm Springs before dawn Wednesday. Less than three hours later, all six died when their car collided with a gasoline tanker on Interstate 5, 100 miles southeast of San Francisco. Killed were Lacetti; Donna Bracewell Holt, 30; Holt's daughter, Kim, 10; Gary Barrs, 27; his daughter, Randi McPherson, 4, and truck driver Kenneth Byrd, 24, of Bakersfield. "I'm usually a hysterical person, but I'm so shocked I can't even cry," said Sheryl Miller, a neighbor and friend of Lacetti. "I just talked to her the other night. I told her to be careful and have a safe trip."