t's late on a Saturday afternoon in March when Heath Ledger walks into the lounge of a posh Hollywood hotel and slumps into a corner couch looking simply exhausted. The 22-year old actor had just completed the first day of interviews for his latest film, A Knight's Tale, the movie that is going to make him a star.   By all accounts, Heath Ledger is a babe from Down Under who has taken North America by storm. He was born and raised in Perth, Australia and at age 10, enrolled in the local theater company. Ledger got his real passion for acting when he joined the Globe Shakespeare Company as a teenager. He starred in everything from productions of Peter Pan to Hamlet while he attended high school.   Ledger was also an avid field hockey player, but it was his coach who told him that he had to make a choice between his two passions. So, at 16, Ledger left home for the big city of Sydney to pursue his career and landed roles in several Australian television series.   In 1997, he got the starring role in the Fox series, Roar, that also starred Keri Russell (Felicity), which was ironically shot in Australia. As a result, Ledger made the move to the United States and starred in the feature film, 10 Things I Hate About You, opposite Julia Stiles.   His performance was so impressive that he was cast in The Patriot, landing the role of Mel Gibson's son. "I learned a lot working on that film," Ledger said. "One of the things that Mel taught me about acting, and life in general, was to relax, take things easy and chill out."   And chill out he has. Ledger is an actor who chooses his projects very carefully. After all, this is a guy who turned down the chance to play Spider-Man because he wasn't passionate about the part and felt Tobey Maguire would do a better job.   After The Patriot, Ledger had dozens of scripts come his way, but it was A Knight's Tale that finally caught his eye. "I think it was pretty obvious when I read it that it was going to be fun to make," says Ledger. "I loved the dancing, the sword fighting, the comedy that was written in the drama, and then the heart. The movie just had a lot of heart and I was just really excited reading this script. It was more about the story, as opposed to the character, which I felt was different than anything else I had read."   When Ledger shot The Patriot he insisted on doing his own riding and as many stunts as he was allowed. The same applied while making A Knight's Tale. "I did anything up to hitting someone or getting hit, but I wasn't allowed obviously to get hit by one of those things (a lance) 'cause you've got to be a little out there. I left that to our stunt guys, who were crazy, but brilliant, absolutely brilliant."   A Knight's Tale was written and directed by Brian Helgeland, the same man who won an Oscar a few years back for writing the screenplay for L.A. Confidential. This is Helgeland's second attempt at directing (after Payback) and he was confident that Ledger was the only actor who could fill the shoes of his lead character.   "I think what first struck me about Heath is that the character in the script had a very strong sense of himself and who he wanted to be, even though he's pretending to be someone else," says Helgeland. "It was very hard to find a young actor who has that kind of self-possessed quality and a strong sense of himself. When I met Heath, he instantly displayed what I was looking for."   A Knight's Tale is going to put Ledger into the leading man stratosphere, but the young actor is humble about all of the attention he is currently receiving and may get in the near future. "I'm just Heath, oddly enough. You know, I really haven't had enough time to think about it and, to be honest, if I did have the time I wouldn't think about it and I don't. So I don't know how I handle it or what's to come and I don't really care - I'm not really worried or thinking about it. I just have fun and I just do my job and then I guess we'll see."   For now, Ledger is quite content spending his time with girlfriend, actress Heather Graham, who is nine years his senior. He says that making a movie together is not in the horizon, but one never knows. Next up for Ledger is a starring role in yet another period piece called Four Feathers. The film is set in the late 1800s and will feature Ledger as a British officer who resigns from the army just before Britain invades Sudan. It will also feature Kate Hudson and Wes Bentley.   After that, he's contemplating his options, but Heath Ledger doesn't have too much to worry about. He's feeling pretty good right now about being a knight in shining armor with his whole future open to endless possibilities. - Bonnie Laufer-Krebs