By Emily Feimster and Stacy Jenel Smith If there is such a thing as an Uber It Girl, Paris Hilton is one. The blond heiress graces covers and fills the pages of celebrity mags and tabloids. Her clubbing, boyfriend relations and party-going have been reported in gossip columns and on television shows. She's been the hottest of internet downloads, with her sexually explicit video romping. And with her hit TV show, "The Simple Life," she has a mass following.\

So it goes without saying that when Paris breaks as a movie star, she'll be hugely successful, right?

No. Not by a long shot.

Paris might get lucky and score hits with her upcoming remake of the chiller "House of Wax" (with It Boy Chad Michael Murray, no less), and her currently-in-production sorority comedy "Pledge This." Or she might not.

It's a mistake to correlate celebrity with box office clout, as many a film investor has learned the hard way.

"New York Minute," anyone? Mary-Kate and Ashley Olsen can sell magazines galore, and just about every kind of merchandise geared to young teen girls - but they couldn't sell tickets to their big-screen stinker, which has yet to break the $15 million mark in domestic grosses.

Demi Moore offers extensive proof that big celebrity doesn't translate to big ticket sales. A magazine cover favorite ("Demi's NEW Plastic Surgery Shocker!" screamed the Aug. 23 Star), she left Hollywood years ago after a string of disastrous movies including the infamous "Striptease," "The Scarlet Letter" and the utter bomb, "Passion of Mind," which failed to surface with even $1 million in U.S. grosses. (Why, that's less than perk-crazy Demi has spent on private jet costs on a picture.) She busted back onto the scene last year with "Charlie's Angels: Full Throttle" but even that much-anticipated sequel failed to make a profit. And as far as leading to other Demi movies, well, it hasn't. But then one must think - here's a 42-year-old woman dating a 26-year-old superstar. Oh, there's no point to that statement, we just recommend you ponder that for a second.

Look at the movie business stats on Madonna, Sharon Stone, Winona Ryder - they each tell tales of women who are more successful as celebrities than as box office bait.

Of course it's not just the ladies of show business who sometimes have difficulty capitalizing on their fame.

Our first male celeb is not only jaw-droppingly handsome but is also one of the most sought-out actors in the biz. We're talking about Brad Pitt, so his movies must bring home the bacon, right? There's "Seven Years in Tibet" which cost an estimated $70 million, but took in only $32 million domestically; "The Devil's Own" which cost $80 million and grossed less than $43 million on these shores; the $90 million "Meet Joe Black," which made just under $45 million domestically, and as much as we hate to keep delivering bad news, there's more! You can talk all you want about "Fight Club's" cult following, but not it's making money. It made back $35 million of its $60 million budget in domestic box office. And don't forget "Spy Game" which you'd think would be a hit because you've got Robert Redford with Brad Pitt -- but even it lost millions of dollars. Brad's most recent flick, "Troy," with an outrageous $185 million budget, has only made $132 million thus far. You can do the math on that one! The good news for Brad is that he's still really hot and is married to Jennifer Aniston, so really he's a winner in life.

Don't go thinking that Brad is the only super hot, super famous guy with box office blunders. There's George Clooney, Ben Affleck, Matt Damon - where should we start? Mr. Clooney made "Solaris," which was a major disappointment, his directorial debut "Confessions of a Dangerous Mind" was a dud, and the hard-to-sit-through "Intolerable Cruelty" wound up in the red.

Ben Affleck's numbers aren't as surprising considering that "Gigli" made a paltry $6 million domestically - at a cost of $54 million. "Jersey Girl" came in the negative as well as "Paycheck." His movie "Bounce" with former girlfriend Gwyneth barely made the cut and "Reindeer Games" failed to recoup its budget. Since "Good Will Hunting," his buddy Damon has also had trouble getting movie goers to watch him perform leading roles. His dopey film "Stuck On You" was a big loser, while "The Legend of Bagger Vance" and "All the Pretty Horses" were in the negative to the tune of $30 million. Damon should be thanking his lucky stars that "The Bourne Supremacy" came along.

So, while celebrity can help a film, it's certainly no guarantee of success. Still needed is that magical combination of script, director and acting talent. Paris, are you listening?