Reprinted from yesterday's late editions.

Staring at the doorway of Potomac House Thursday night, Margaret Wimsatt, co-chairman of the preview party for the 1977 Decorators' Show House, looked momentarily amazed.

"My God, I don't believed it. Rostropovich did bring that dog of his after all," she said as she watched the arrival of National Symphony conductor Mstislay Rostropovich with his dog, Pooks. "Oh, well, I just hope the dear little thing is housebroken."

Apparently, he was - or at least Pooks managed to contain himself long enough to get through the following hour while members of the women's committee for the National Symphony Orchestra, accompanied by Ambassador and Mrs. Age R. Tammenoms Bakkar from the Netherlands, gave the Maestro and his daughters, Olga and Elene the VIP tour of the show house in McLean.

The preview party, an annual affair signaling the opening of the Decorator's Show House (open to the public beginning today through Oct. 23), drew, besides Rostropovich, nearly 550 guests at $50 a head. For that price, the crowd was free to help themselves to a buffet and wander through rooms that local decorations, taking one room each, had transformed in their own vision and at their own expense to benefit the National Symphony. Potomac House, inspired by Carter's Grove Mansion near Williamsburg, is owned by Potomac management and is currently on the market for $3.2 million.

For his part, Rostropovich pronounced each room he passed through as unqualifiedly "R-e-a-l beautiful," although his favorite was clearly the music room designed by Jacqueline-Antone Interiors and named for Olga and Elena, who are students at Juilliard in piano and cello, respectively.

Reaching the music room, Elena tickled the committee women by presenting them with a dried nosegay from her first appearance at Tanglewood two years ago.

Following up, her exuberant father insister that Pooks go into his standard act and pick out a few notes on the keyboard before Rostropovich signed a copy of a sonaia that sat on the piano.

But it didn't sit there for long. Immediately after Rostropovich and the crowd left the room, committee women replaced the music book, fearing, said one, "that some Rostropovich crazy might take this for a souvenir."

Madame Rostropovich, Galina Vishnevskaya, did not join her family Thursday night because, explained Elena, she was in London rehearsing to sing "Tosca" at Covent Garden, "My mother," she added, "is the most beautiful woman I have ever met. And fater? Ah, he is my brother, my sister and my father all in one."

Meanwhile, Sarah Lee Howell, this year's overall chairman for the Decorators' Show House, pronounced the affair a smash. "We even got the driveway paved this week. No, I won't tell you how we paid for it, but let's just say we girls were determined that no expense would be spared to make this "this show" the best one ever."

And added Howell, purposely dressed in gray jersey to match the gray muralled walls of the stairway hall: "This is the first year we've had a house in Virginia, you know. We thought by picking a new house, it would be a quite challenge."

Apparently, because when the women first saw Potomac House last January it was a mess. Its construction, began by Louis Pomponio several years ago, had been abandoned until last year when Potomac Managemen, took it over and offered it to the committee for the show.

Unfortunately, however, Pomponio could not be there Tursday night. He is currently in jail serving out a three-year conviction for bribery.