The wrestling federation from Korea was the first nation to send in its preliminary registration to compete in the 2003 World Championships of Freestyle Wrestling in New York City, 12-14 September.    The tournament will feature the world's best men and women freestyle wrestlers, competing in the world's most famous sports arena, Madison Square Garden. The World Championships of Freestyle Wrestling is also a qualifying event for the 2004 Athens Olympic Games. Women's wrestling will be contested in the Olympics for the first time ever in Athens.    Korea indicated that it will send a delegation of 20 individuals to the World Championships, including seven athletes in  men's freestyle and four athletes in women's wrestling. Korea is a world power in men's wrestling (both freestyle and Greco-Roman), and is developing a competitive women's program.     At this time, nations are not required to present their preliminary athlete rosters for the World Championships. As team rosters are received this summer, they will be announced to the public.    "USA Wrestling and the organizing committee are excited that Korea was the first nation to indicate their official participation in the 2003 World Championships," said USA Wrestling Director of State Services Mark Scott, the Competition Director. "We expect up to 70 countries to enter the championships, which could develop into the most prestigious and exciting World Wrestling Championships ever."    Two other nations, Estonia and Switzerland, sent in their preliminary registration forms this week and will send competitors to the 2003 World Championships of Freestyle Wrestling    Estonia indicated that it will send a six-person delegation for the men's freestyle competition, including three athletes.     Switzerland has decided to send a full seven-athlete men's freestyle team and three athletes for women's freestyle, with a total delegation of 15 person.    More nations are expected to send in their preliminary registration forms in the upcoming weeks in order to meet a May 30th deadline.    Tickets are on sale now for the 2003 World Championships of Freestyle Wrestling. Organizers are expecting a sellout for the Saturday and Sunday sessions. To get the good seats now, call 1-877-NYC2003.