After the incense cleared and he ancestor worship ceremony was over the 700 Vietnamese settled into their seats at Arlington's Jefferson Community Center yesterday for some light entertainment.

A husband and wife duo came onstage and soon had the audience laughing at their patter about the occasion, the Vietnamese lunar New Year known as Tet -- and listening intently to the songs that were sung in Saigon before it fell to the Communists.

One of the Vietnamese spectators leaned over to an American acquaintance and nodded toward the performers. "They're professional singers," he said."They arrived here about six months ago from a refugee camp in Malaysia. Boat people. We're lucky to have them."

Even at the happiest moments, such memories of tragedy are close at hand for the 20,000 Vietnamese refugees in the Washington area. But Tet is a time when old debts and problems are supposed to have been resolved and there is a sense of renewed opportunities.

At this year's celebrations especially, there was increased talk among Vietnamese of helping themselves to adjust and prosper in American society.

The celebration in Arlington yesterday was sponsored by the Vietnamese Senior Citizens Association, a group that has grown from 36 to 181 members in just over a year, and is dedicated to helping older Vietnamese in the area adapt to American life.

At the Washington Buddhist temple on upper 16th Street NW where another Tet celebration took place last night, an organization called Buddhist Social Services has been formed to help with the enormous job of resettling the thousands of Indochinese refugees who will be coming to the United States.

Hiep Lowman, the Vietnamese wife of the State Department's director of refugee affairs, has been a principal organizer for both groups. Yesterday, she said some Vietnamese who originally opposed such undertakings have ended their opposition to the efforts.

"... I told them," Lowman said, "the Americans help us so much and some of them love us so much, but it's not their job. It's our job to take care of ourselves." Though the resettlement organization is still hurting for money, Lowman said it will be handling at least 20 refugees next month, and the number should grow after that.

Another community activist, Nguyen Ngoc Lieu, works as liaison between Arlington's Barrett Elementary School and the families of about 50 Vietnamese children who attend it. His most difficult task, he said, is to assuage tie fears of parents, still tied to Vietnamese traditions, who see their children rushing headlong into the American main-stream.

"The children want to be the same as American children," said Lieu. "They don't want to be strangers in the school.... The parents often try to hold them back. But that is the reality they must deal with."

No one expressed any illusions yesterday, however, about the size of the job before them. The shock of losing their homeland still lingers with most Washington Vietnamese.

As the singer onstage in Arlington moved from jokes about the difficulty of learning English to a song about her love for her own language, the audience fell silent.

"I think," said one elderly man "that she is trying to put all the audience in the same mood -- homesickness -- and she has succeeded."