When the season premiere of "Dallas" airs next week, it will carry an unusual commercial message: Prince George's County schools are better than you think.

The locally broadcast ad is part of a high-powered campaign sponsored by the county's business community to enhance the tarnished image of its school system. Business leaders hope the slick public relations blitz -- also set to run with "Hill Street Blues," "60 Minutes" and other prime-time hits in coming weeks -- will ultimately attract new firms and homeowners to the county.

"There's no question that there are people who have chosen not to live in this county because of things they've heard," said Charles A. Dukes Jr., chairman of John Hanson Savings and Loan and a primary force behind the media campaign. "We don't believe that most people are getting anything like a fair picture."

The advertising effort, scheduled to be announced at a news conference today, includes three commercials, each depicting a present or former county student who has excelled in science or art. The ads represent an image that organizers hope will replace the more common perception of a system beset by problems of desegregation, low teacher morale and persistent financial problems.

The 30-second spots are to begin running tonight on five television stations, continuing through Oct. 3 and resuming in January.

Weitzman, Dym & Associates, the Greenbelt-based public relations firm that produced the ads, estimates they will be seen by 97 percent of the 1.2 million Washington-area households with television sets.

The cost of airing the ads would normally be about $135,000, but as a contribution to the effort, the stations sold the time at a discount of 25 percent to 35 percent. Also, Weitzman, Dym sold the commercials at cost, about $58,000, instead of its normal rate of more than $100,000.

The ads will run with each of the three network morning news programs, two nighttime specials and a slate of weekly regulars. They will run on each of the three major Washington stations, channels 4, 7 and 9, and on Channel 5 and Channel 20.

The effort by business leaders comes as the school system undergoes massive change. School Superintendent John A. Murphy this year implemented a magnet school program designed to end the county's 13-year-old desegregation lawsuit, introduced new academic programs and restructured his organizational chart.

"We're on the move. It's sensed in the business community. It's sensed in the political community," said Murphy. "Unfortunately, most of the attention has been focused on the negative . . . . If we're ever going to get a successful school system, it all begins with attitude and a proper perception of what is happening in the schools."

Led by Dukes and Winfield M. Kelly Jr., who heads a committee appointed last year to encourage cooperation between business and education, the business community has already raised $115,000 and hopes to bring in another $85,000 for the ads. Donations were solicited at a fund-raising breakfast last week and a similar event is scheduled next month.

Contributors include PEPCO, a major employer in the county, John Hanson Savings and Loan, Kelly's cable television company, the Suburban Maryland Homebuilders and the county's Board of Realtors.

Dukes said the business sponsors considered spending money on equipment for schools or more conventional contributions but decided against it.

"If we raised $200,000 and decided to go out and do something in the schools, it's gone," he said. "If we can have any contribution . . . . toward raising image and morale . . . in the long run, you'll be able to do more."