CALGARY, FEB. 25 -- By now, we all know professionals participate in the Olympics.

Swiss skier Pirmin Zurbriggen, who made about $2 million last year, will have an estimated $1 million windfall from sponsorships and endorsements because of his victory a week ago Monday in the men's downhill. The figure could be even higher for flamboyant Italian Alberto Tomba, who won today's giant slalom and is the favorite in Saturday's slalom.

Hockey players Randy Gregg, a defenseman, and Andy Moog, a goaltender, both of whom played for the three-time Stanley Cup-champion Edmonton Oilers, are in these Olympics, playing for their native Canada. Moog was given $200,000 by a Canadian food store chain to take time away from the NHL and play for his country.

And Steve Leach, a forward on the disappointing U.S. Olympic hockey team, is the same Steve Leach who played 15 games for the Washington Capitals last season.

It's happening in hockey. It's happening in skiing. It will happen in tennis, track and field and soccer in the Summer Olympics in Seoul.

It's happening because the International Olympic Committee decided two years ago that it was time "to be realistic; time to get in line with what's happening in the world," said IOC spokeswoman Michele Verdier.

It was time to let professionals play with the amateurs.

This is the first Olympiad at which professionals openly have been allowed to compete (although pros or state-supported athletes have been in the Olympics for years). The decision on a professional's availability and eligibility rests with the international federation of each sport. The IOC has washed its hands of the situation.

The International Hockey Federation says it's all right for professionals to compete. Because of the poor performance of the U.S. hockey team here, there may be more and better-known NHL players on the U.S. team in 1992.

Things are a bit different in other sports. The world's top skiers make big money from endorsements and sponsorships, but, almost always, their money goes through their national team and a fraction is taken away for the team. Trust funds have been established in countless winter and summer Olympic sports. If the money is channeled through something, so the theory goes, it's okay for the athlete to take it once he or she retires from the sport.

In basketball, some nations will have pros playing for them in Seoul, although the NBA hasn't yet decided to let the Michael Jordans and Larry Birds play for the United States. The elite players may never join their nation's Olympic team, just as Wayne Gretzky did not play for the Canadian hockey team in these Olympics. But some of the better players just might.

In that case, the NBA must decide, as the NHL did, how to allow players to leave their teams during the season and play for the national team. The NHL told its teams to make a list of their 10 best players and the Canadian and U.S. Olympic teams could pick from the remainder of the players.

The genesis of the "open" Olympics was increasing Western dissatisfaction with the state-supported teams from the Eastern bloc. U.S. corporations began to get involved in sponsoring athletes and whole teams; all-out professionalism was soon to follow.

"The main belief is that the Olympics should be a forum for the best athletes in the world," said U.S. hurdler Edwin Moses, a two-time Olympic gold medalist who sits on the IOC Athletes' Commission. "Each international federation has different criteria . . . Amateurism as we knew it five or six years ago does not exist today. There are pros in the Olympic Games."

Ken Read, a former Olympic skier for Canada who also is on the athletes' commission, said it's wrong to assume many of the skiers at Nakiska are making hundreds of thousands of dollars.

"There are 200 to 300 athletes out there and, of that, maybe 30 make over $50,000," Read said. "National teams do it differently. With the Canadian team, money made by the skiers goes into the general revenue fund and ends up financing another two or three skiers to compete. A skier like Rob Boyd would get to keep 75 percent of his money, but 25 percent is kept by the team.

"If there was open professionalism in skiing, the sport would collapse," Read said. "It's so horrendously expensive to compete, to travel, to pay a coach, that what would happen is only a few of the top skiers would be able to go on. That's why it's good a portion of the money earned by skiers from sponsors and manufacturers goes back to the team."

Read said it was time to allow professionals into the Olympics and time to allow "amateurs" to earn money.

"There was the hypocritical aspect of state-sponsored amateurs and Western amateurs," he said. "How could you weigh the differences? The IOC decided it was time to allow everyone in. I think that was only fair."