Carol Busby spent much of last year selling spices, planning flea markets and organizing bake sales, gradually gathering the profits to write a check in September for nearly $3,000 -- the cost of three Apple computers and three Commodore color monitors.

Busby, president of the Glebe Elementary School Parent-Teacher Association, and other Arlington parents were somewhat stunned when they were told that the county School Board had decided to put computers in the county's 19 elementary schools. The computers the Glebe PTA had purchased, still in their packing crates, would count toward the total number the school would get from the board. So while other schools -- each having at least one computer already -- would get five computers each from the board, Glebe would get only three.

After a flurry of PTA protest, the board reversed itself and announced it would give each school four computers, no matter how many were in the schools already.

"It was very hard for us to raise that kind of money," Busby said last week. "I understood what the School Board was trying to do -- trying to address the disparity between elementary schools. But I felt bad that we were going to be penalized."

The Arlington decision was not the first time a school board has struggled with the sticky issue of PTA gifts to the schools. Throughout the Washington area, parent-teacher groups with varying abilities to raise money can affect the quality of educational materials in their schools. One group may raise money for five computers, while another can afford only one; one playground may be equipped with fancy new jungle gyms, slides and swings, while another is barren or the equipment is rusty and old.

"I sure promote PTAs being involved in doing things to help the schools," said Arlington School Board member Frank K. Wilson. "But at some point, we have to look at our instructional programs and make sure a PTA is not doing something that is going to make a school academically better off or worse off."

Many area school board and PTA members say that they are troubled by the inequities that PTA gifts create. Those imbalances are compounded, they say, because the students in less affluent neighborhoods, where PTAs may be less likely to give large amounts of money to the schools, are also most likely to be the children who don't have books or educational toys or computers in the home. However, most officials agree that there is little a school board can do to "even out" the acquisitions for schools.

And, in a time of tight budgets and nationwide stress on private contributions to education, school systems must suffer the imbalance created by PTA gifts because they can't afford to do without them.

"Many years ago, PTAs did not give instructional materials to the schools," said Sarah Johnson, vice chairman of the Prince George's County Board of Education. "But now we don't have the money and parents want things for their kids. And we are grateful."

"With a school system as big as ours, with 105,000 students, we sort of welcome any help we can get from the PTAs," said Angelo Castelli, chairman of the Prince George's school board.

The nature and magnitude of PTA help varies widely. Many groups routinely buy library books, pay for field trips to the Kennedy Center or create discretionary funds for principals and teachers. Others spend money on more unusual projects, such as the $2,000 art gallery complete with track lighting, framed reproductions of master artworks and pedestals for students' work in Fairfax County's Canterbury Woods Elementary School.

In addition to contributions that are purchased, parent-teacher groups also contribute to schools by volunteering for such tasks as planting gardens on school grounds, tutoring and sponsoring seminars on subjects they are expert in, said Conchita Mitchell, president of the Arlington County Council of PTAs,

According to local school officials, there are few limits on PTA purchases, although some areas, such as the District, require an annual report of the gifts each school receives from outside sources.

But, lacking stringent written guidelines, many say PTA purchases should be confined to "supplemental" rather than "essential" materials. William Brown, president of the District of Columbia Congress of Parents and Teachers, said he advises PTAs not to spend money on textbooks, draperies, pencils or general school maintenance. "Those things should be provided by the system," he said.

Nancy Dacek, president of the Montgomery County Council of PTAs, noted that raising money and buying equipment for one school is often quicker than lobbying the school board to provide the material for everyone in the system.

In the computer matter, said Cathy Belter, first vice president of the Virginia Congress of Parents and Teachers, "the PTAs were seeing this technology coming on the scene; the school board has to take its time. A lot of parents felt very strongly that their kids had to get into this right away."

That urgency sometimes is at odds with the aims of the school boards. "I have a very basic philosophy in terms of being a school board member . . . . I'm going to try to do the very best I can to make things equal throughout the system," said Wilson of the Arlington School Board.

In theory, the PTA, too, is meant as "an advocate for all children," said Pearl Lineberry, president of the Virginia Congress of Parents and Teachers.

But in practice, especially in smaller school districts where the activities of each school's PTA are very visible to the others, "there probably will be some competition. It's probably in a way like sibling rivalry," said Lou Cook, chairman of the Alexandria School Board.

Some school officials have tried to cool such competition by encouraging businesses to "adopt" schools with less active PTAs or allocating equipment first to schools where PTAs have not purchased items for the school. But most board members agree that school boards cannot afford to restrict PTA gifts in a struggle for balance.

"There's no way you can set a policy that evens everything out," said Cook. "That's just the way life is."