It's a typically tantalizing, sunny-side up spring morning on Santa Monica beach. Sea- gulls troll for breakfast, strollers comb for treasure, models slouch for photographers, and Julianna Margulies--well, she's looking a little queasy. "I just got my first million-dollar movie offer," the 28 year-old ER star confides during a coastal walk. "It was amazing...but I turned it down!" A burst of nervous laughter erupts; her stride starts to wobble. "If I think about it too much more," she warns, covering her flushed face with her hands, "I'll throw up."

This Maalox moment is brought to you courtesy of the dizzying star momentum and healthy ambition of Ms. Margulies. Her Emmy-winning role as emotional ragamuffin-turned-guiding light Nurse Hathaway has fueled the watercooler chatter (What's up with her and Shep? Will her suicidal tendencies resurface?) that propelled ER to new heights its second season: Television's No. 1 series drew an average of 32 million viewers per show--surpassed only by the 1986-87 seasons of Murder, She Wrote and Moonlighting--and locked up the highest-ever cable syndication deal per episode ($1.2 million for 88 shows from Turner).

As if that weren't enough to fibrillate her heart, Margulies also finds herself taking stomach-churning career gambles. For example, rather than star in any number of chick-in-jeopardy TV flicks (with enticing six-figure paychecks), the actress took $50,000 to play a bartender who tangles with grifter Bill Paxton (Twister) in the romantic movie thriller Traveller (now seeking a distributor). And when she could have pocketed the aforementioned $1 million for the lead in a big-studio action-adventure (the name of which she won't divulge), she jumped instead at a $150,000 supporting role in the Bruce Beresford-directed Paradise Road, a Fox Searchlight drama about World War II POWs starring Glenn Close and Frances McDormand. "I don't need the money right now," reasons Margulies, who, this month, is filming in Australia. "I don't have kids to support. I don't own a home. My focus is, Who are the people I want to work with?"

Apparently the same people who want to work with her. "She's a classic '40s movie starlet," raves Paxton. "She's exotic, sultry, and voluptuous, but there's also this earthy, warm congeniality about her. She's gonna be the It Girl." Enthuses ER exec producer John Wells: "Julianna's got enough energy for six people. She has a tremendous intensity and enthusiasm that's very infectious. She's the fire."

The flames burn especially bright when the subject is Hathaway. Margulies takes pride in her character--who's peeled more layers than an overworked dermatologist--and wasn't shy about fighting for shifts in plotline this season. "We made a conscious effort to lighten Hathaway up," says Wells. "We wanted to show that [she's more than] post-suicidal angst and longing looks at George Clooney." In fact, the object of lust this season was paramedic Shep, though Margulies insisted he shouldn't become Hathaway's focus. Otherwise, she says, "there was no arc. You can't have a character who's tried to commit suicide, who's had an incredibly tempestuous relationship, who's been dumped at the altar, and then just put her with a guy and make it all about him." Even Wells now concedes she had a point, noting "her concern about being tied to Shep was realistic."

Ironically, that tie binds her off screen as well; the tabs and sources on the show say she dates Ron Eldard, who plays Shep. And just as she's outspoken about not turning Hathaway into a one-dimensional lover, Margulies fears the same in her own life: "Suddenly it's all about the relationship and not your work or who you are." In other words, she'll cop to only the basics of her bio--that she's the youngest of three daughters born to a now-divorced dance teacher and an ad exec, was raised in England and New York, and now lives in Santa Monica--while remaining tight-lipped on the juicier details. "If you want a love story," she responds with a shrug, "rent one."

Eldard--whose character may or may not be back next season (he's starring in NBC's fall sitcom Men Behaving Badly, in any case)--won't confirm an off-screen relationship with Margulies but will expound mightily on her passion: ''It comes out in everything she does--her acting, the way she laughs, even in her knitting. In the pilot she had very few lines, but she filled it with her power and purpose.''

Passion spiked with purpose marked her lackluster early career. Before ER, the Sarah Lawrence grad's infrequent acting gigs (including a McDonald's Hot Wings commercial) were supplemented by waitressing jobs. In one particularly unnerving stretch, she failed four consecutive sitcom tests in one month: "And I'd been told I was funny," she deadpans.

Margulies' rise from oblivion began with a voice mail message from Clooney: "Your character tested through the roof. Don't take another series!" Actually, she was then agonizing over an offer to star as a generic vixen in a Malibu beach series. Should she go for the sure thing or risk the maybe? "I'd rather go back to waitressing than play a character that I hate," she recalls deciding. Good choice. The call from ER came a few weeks after Clooney's--on her 27th birthday.

While Nurse Hathaway would make a full recovery, Margulies didn't feel like a real hospital staffer for many months. "I kept fighting the fact that nobody knew who I was," she says. "Even toward the end of the season, there was a thing on the news--'What the ER Actors Were Doing Before ER'--and it showed all the [main characters] but me."

Vindication came last September, when Margulies was singled out as the show's only star to earn an Emmy. "Winning Best Supporting Actress," notes Wells, "was validation that she really belonged." Indeed, her walk to the podium was something of a religious experience: "My feet weren't attached to my body. Then I saw [presenter] David Duchovny. He has these incredible eyes, and I was like, 'Just stare at the eyes, stare at the eyes.' The rest was in slow motion."

Thanks to her newfound notoriety, Margulies finds even mundane moments turning surreal: "You're just pumping gas, not knowing if a guy's looking at you because he thinks you're cute or because you're on the show." The professional ors--Is this the right project or is that one?--also keep her second-guessing. "There was this Sidney Sheldon miniseries," she says, returning to familiar angst. "My first reaction was absolutely no, and then I'd go [gasping for breath], 'My God, you just turned down half a million dollars! Are you out of your mind?'"

Perhaps. But there is a method to her madness. In predictable TV star fashion, she's banking on a big-screen career. "I'm holding out for the quality parts," she says. "I don't want to crash and burn before I've gotten to where I want to go. I want to enjoy the ride." May we then suggest a travel-size bottle of antacid?