How do you decide what Christmas present to buy for a finicky boyfriend who likes Oxford shirts but despises button-down collars? Or how about for the new son-in-law, a commercial fisherman who's getting a college degree in food technology? How do you shop for a 14-year-old preppy playmate when you only have $10 to spend? And what about for a 71-year-old chief executive named Ronald who has everything?

And what do you do if you're a little-known computer company, looking for a way to get your name before the public?

Answer to all of the above: Christmas shopping by computer.

Computers are already outstripping Orwellian fantasies, matching up compatible lovers, ordering motorists to fasten seat belts, paying bills, sorting mail, answering telephones.

Now computers can help man in such an intimate endeavor as finding perfect gifts for friends and loved ones.

Three red, desktop computer terminals and printers are stationed strategically around a shopping mall in Bethesda, under a red and white "Shop by Computer" display sign. To bewildered onlookers, the warmly glowing words on the screen entice the curious with the introduction: "Welcome to Montgomery Mall . . . I hope to make holiday shopping easier for you this season."

Darcy Infante took up the invitation. The bubbly 18-year-old from Rockville had been criss-crossing the mall all afternoon, clutching the arm of her boyfriend's best friend, searching for that perfect something for her sweetie 500 miles away at Michigan State University.

"I want to get a present from my boyfriend," Darcy said, "but I'm stuck. We've been here for quite a while. The problem is, he's so picky. He's the hardest guy in the world to shop for."

So Darcy followed the instructions, entering the name of her beau, Tim, his age, 18, and her price range, under $50. She also picked out his life style from a list of nine categories provided: athlete, all-American, studious, mechanical, homebody, executive, trendy, preppy and collector. For the truly rugged and hard-to-peg individualists, there is an additional category called "not listed." Darcy chose athlete.

Flashes of light, whirls of microcircuits. From the printer spewed a list of gift ideas for Tim: a $50 Levi's fur-lined jacket, available at a nearby jeans store; a $50 savings bond from the bank across the foyer; a pair of $39 designer jeans from a pants store; a $40 camera; a pair of boots; have his baby shoes bronzed. "That's ridiculous," Darcy huffed.

The computer has more than 1,500 items in its memory, according to Ken Chisholm, its human sidekick and press spokesman. The gift list is provided by the mall merchants, and prices range from under $10 to a $100-and-up category.

The gifts run the holiday gamut, leather jackets and cassette players and gold hoop earrings and, for $2,325, a Rolex watch.

Marian Chapman waited intently for the computer to spit out its suggestions for her son-in-law, a commercial fisherman-turned-food technology student. "I haven't a clue what to get him," she sighed. "I put in that he's mechanical."

Out came her answer, the last item on a list of 12. "I know what to get him!" Chapman exclaimed. "I'll get him one of those vibrating brass shower heads. Very good. It works."

"Most people find one or two items on the list they haven't thought of," said Chisholm. "I've had it happen a few times where one of the items on the list they'd already bought."

Another lucky computer shopper was 14-year-old Jane Racoosin, who was searching for a present under $10 for a friend she described as "preppy." And what do you buy a 14-year-old preppy this year? A pair of leg warmers, of course, in assorted colors (Like, totally tubular, y'know?). Or a pair of $5 pierced earrings. Or custom bows in assorted sizes. Then there's always a designer belt, a poster, or a jigsaw puzzle, or -- gag me with a spoon -- some deluxe chocolate syrup.

For a 71-year-old executive named Ronald, when the shopper had only $100 to spend, the computer was at first stumped. After a few excruciating minutes, the gift suggestion list began to appear, topped by a $100 high-rate certificate from a local savings and loan, followed by a velour terrycloth hooded robe. Also on the list were a whirlpool bath, a Pierre Cardin jacket and a $100 porcelain plate.

Neither cowboy boots nor jellybeans appeared on the chief executive's gift list.