Tonight's the night. After a fevered few weeks of Youtube hits and Oprah interviews and makeovers, tears and tantrums, Susan Boyle will take a deep breath and sing for the public's votes in the final of Britain's Got Talent.

Ever since that remarkable audition in April when she surprised the judges of the ITV show with a dramatic performance of I Dreamed a Dream from Les Miserables, the 48-year-old from Blackburn in West Lothian has been the favourite to win.

It's been good for ITV, good for prime-time entertainment and certainly good for Simon Cowell, but now questions are being raised about how good it has been for Boyle.

Yesterday, the producers insisted their star was getting the support she needed following reports that she had packed her bags and was struggling to cope. Judge Piers Morgan admitted that Boyle was finding it difficult.

"She has been in tears many times during the last few days," he said, "and even, fleetingly, felt like quitting." There are fears over how she might cope with the success - or perhaps failure - to come.

Michelle McManus knows a little of what Boyle is going through because she went through the same thing. Six years ago, McManus, 29, was the unlikely singing star who auditioned for Pop Idol. She won, but was dropped by her record label three months later. Since then, she has built a career for herself but clearly has big reserves of toughness that perhaps Susan Boyle does not.

"Susan has lived in a small community all her life and is a vulnerable person," says McManus. "I hope the record company is not there to exploit her. Exploit is a strong word but that is what they do. You have to remember this is a TV show and a money- making exercise for ITV and entertainment for the public."

McManus says what happens when the final is over is crucial. "If Susan is left to her own devices, they will have exploited her," she says. The producers have a responsibility, she says, but Boyle also needs to approach the next few weeks with the right attitude.

"Susan will make those people money. When you win a show like that you have no-one to answer to and that's hard to get your head round. Susan has to remember she's the head honcho."

Of course that is easier said than done for Boyle, who has some learning difficulties. Dr Laura Mitchell, a psychologist at Glasgow Caledonian University, says the unreality of a reality show would make anyone feel anxious. "For any of us, being transported into these surroundings makes you feel vulnerable but she is getting a double whammy because she's in a situation that's got a high level of public scrutiny," said Dr Mitchell. "She has maybe not had a hugely varied life experience in terms of social experience and travel to develop the confidence that someone else would have."

Dr Mitchell also said it was probable that Susan was developing fearful thought patterns because of the stress of her new life. "We call it catastrophising, the intense fear of being criticised and something negative happening to you."

Dr Mitchell said proper support was vital for the reality star, something those in the industry agree with. Alex Papasimakopoulou and Sally Grummitt of Everymatic music PR company in Glasgow both say Boyle has a career to look forward to.

In fact, Alex believes that with all the promotion she's getting in the US, the producers could sell millions. "Whether Susan wins or not, there will be an album, but hell knows how this woman is going to come out at the end of it all."

Sally also believes a career beckons. "She might bash out a couple of albums of classic songs and do a duet with Gary Barlow with Comic Relief or something."

But Sally isn't clear how long the spotlight will burn or how bright. "It's about how savvy her team is," she says.

It is clear though that you can win Britain's Got Talent and do well. Two years ago, Paul Potts was just like Susan Boyle. He is releasing his second album on Monday. He recognises that the show exploited the fact that he and Susan don't look like average stars. "Of course that was a factor. I knew I didn't look like the archetypal pop star, which was why I wondered whether the show was the right thing to do. "

He too says the most important factor for Susan now is support. "She will need guidance on how to deal with the changes in her life."

Those changes have already started - and no doubt there are many more to come.