'My wife and I were happy for 20 years. Then we met," goes the stage-old joke. But for some, that's so accurate, it's unfunny. And for celebrities, the chances of a Happy Ever After are as likely as a sad ending in a Hollywood movie.

It's hard to think of anything that would make Pulp Fiction star Uma Thurman nervous. But she recently admitted that her impending marriage to Swiss financier Arpad Busson is giving her a little more than the usual butterflies. This will be her third trip down the aisle but Thurman doesn't have the monopoly on the 'already-jilted' jitters. "Everything makes me nervous -- except making films," said fellow actress Elizabeth Taylor once, but that didn't stop her doing the wedding waltz no less than seven times.

Still, you can understand former-Buddhist Thurman's apprehension: she was briefly married to actor Gary Oldman in the early 1990s, but his alcohol-fuelled sprees led to a split after just two years. Six years later she married Ethan Hawke, and when asked by Oprah if there was any betrayal involved when things came to a nasty end, she merely replied: "There was some stuff like that." Earlier this year, he married their former nanny.

And now her choice of 'third man' is a bit suspect: known as a 'playboy' even to his own friends, Arpad Busson has had a string of high-profile girlfriends, most notably supermodel Elle McPherson, with whom he has two children. In London, he hangs out with Madonna and Guy Ritchie. He once had a highly publicised romance with actress Farah Fawcett. And rumour has it that he saw Thurman in Pulp Fiction and told a friend: "I am going to marry that woman some day.''

Such hero worship would have the rest of us uploading his profile on crazystalkers.com, but our Uma was like a moth to the flame. Like most actresses, she thrived on the idolatry.

You would think Uma might have learned her lesson by now: celebrity marriages are tough work. And her admission that the thought of wedding Arpad is scarier than a Tarantino plot doesn't exactly bode well for the relationship. Yet, some celebrity duos work a treat, although they are relatively rare, and such marriages are usually referred to as 'long-lasting' and 'enduring' ad nauseum.

The marriage of Paul Newman and Joanne Woodward is the perfect example. They celebrated their 50th anniversary in January and have been the envy of many of their peers. They met in 1953 and married five years later. Joanne says it works because Paul is "romantic and considerate" and her hubby says it's down to "patience and affection".

But Paul has also offered some words of wisdom: "Husbands and wives should have separate interests, cultivate different sets of friends and not impose on the other ... You can't spend a lifetime breathing down each other's necks."

Of course, we can't forget the well-documented love of Paul McCartney's life: Linda Eastman. They met in 1967 at the Bag O'Nails in London. Paul claims he was attracted by Linda's smile. She went back to New York City, and they didn't meet again until a year later, but were inseparable until her death in 1998. "Every love song I write is for Linda," he once wrote. Indeed, the romantic gesture is a theme that regularly rears its scented head in stories of star-struck stars time and time again.

Judi Dench's actor husband Michael Williams is reputed to have sent her a rose every Friday of their lives together, until his untimely death from cancer in 2001. They met in the early 1960s at the Royal Shakespeare Company.

Meryl Streep, who married musician Don Gummer in 1978, says that "listening" to each other is the key to a good relationship, but she has also hinted at the fact that it helps being married to another 'celebrity': "My husband understands the compulsion to create things. With somebody who had a regular job, I think it might have been harder to translate those creative impulses and the need to satisfy them."

There is another important feature that many happily married celebrities say could be the key to success -- laughter. "Always get married early in the morning. That way, if it doesn't work out, you haven't wasted a whole day," said Mickey Rooney some years before meeting his current -- and most long-standing -- wife, Jan Chamberlin.

Jan says Mickey makes her laugh, and that is one of the secrets to their much-hyped success, after his other seven 'short' marriages. Jan and Rooney married in 1978 and are still blissfully happy. "I'm the only man in the world with a marriage licence that says 'To Whom It May Concern'," he once joked.

You get the feeling there are also a few laughs in the 24-year marriage of director Joel Coen and actress Frances McDormand. When asked by a reporter how she got the part in Fargo, Ms McDormand replied: "The fact that I'm sleeping with the director may have something to do with it."

If laughter is the best marital medicine, what is its perfect poison? One theory is the 'two-kid itch'. Several formerly happy twosomes became misery central as soon as they expanded into foursomes, it would appear. Alex Rodriguez, currently in the news for his alleged liaisons with Madonna, was spotted lapping it up with an exotic dancer in Toronto just weeks after the birth of his second child. He has since split with his wife, Cynthia.

And how about Britney and Kevin? She filed for divorce exactly a month after second child Jayden James was born. Less than two years after having her second baby, actress Reese Witherspoon announced she was in marriage counselling with husband Ryan Phillippe. A year later, they separated.

The 'bust-up baby' phenomenon has struck fear into the hearts of friends of seemingly 'perfect' celeb couple Courtney Cox and David Arquette. They have been the constant picture of wedded bliss since their marriage in 1999. Already the proud parents of Coco, last year the couple announced they were undergoing IVF in an attempt to conceive their second child.

The writing is on the wall, Uma. Before you exchange gold bands with the millionaire playboy, remember the rules: just one baby, be romantic, creative and sensitive. But most importantly, start writing that pre-nup. At least if it's third time unlucky, you could be laughing all the way to the bank.