For much of yesterday morning, Aileen Gilbert stuck to the business at hand: registering voters who were streaming in for the Barack Obama rally in Monaca.

But shortly before noon, when the Illinois senator entered the hall at Beaver County Community College for his first appearance in Western Pennsylvania as a presidential candidate, the normally level-headed Ms. Gilbert lost it.

"Whoo! Oh my God! Help me, help me, help me!" the 57-year-old Aliquippa resident shrieked, as the crowd cheered and her companion, Dawn Montero, 47, made a show of fanning her overheated friend.

It was perhaps the most vocal display of abandon during Mr. Obama's nearly one-hour appearance, a sold-out town meeting billed by his campaign spokesman Sean Smith as a "smaller, more intimate type of event" rather than a big speech -- even though nearly 1,000 people bought tickets.

Mr. Obama was received warmly if not wildly by the crowd in this solidly middle-class part of Beaver County, which included students, retirees and, most tellingly, a number of open-minded but cautious voters identifying themselves as Republicans and Independents.

"I'm here to see what he has to say," said Paul Lengyel, 48, of Moon, a Republican who cited national security and the war on terror as his main concerns.

He said he will vote in the Republican primary but may vote for a Democrat in November.

Also curious was Dan Dreyer, 61, of Chippewa, an Independent who plans to register as a Democrat so he can vote, he says, for Mr. Obama's opponent for the nomination, Sen. Hillary Rodham Clinton, D-N.Y.

A retired federal employee who lived in Washington, D.C., during the administration of former President Bill Clinton, he said, "I thought he did a good job as president, and she's very competent. Smarter than he is, in fact. But Obama may still get the nomination, so I figured it was time to get a little fix on what he stands for."

During his question and answer session, Mr. Obama was asked about his position on health insurance -- a top preoccupation cited by voters interviewed before the event-- abortion, veterans' benefits and student loans.

Many found the Illinois senator's honesty refreshing. When one questioner complained about the difficulty of living on veterans' benefits, Mr. Obama was sympathetic but noted, given the current deficit, "the truth is I don't foresee a huge expansion of benefits coming out of the budget."

And when a college student asked when her middle-class parents might be able to qualify for financial aid, Mr. Obama cited his proposal to provide $4,000 to help eligible students pay for college while lamenting that free college for everyone would probably be impossible.

Michelle Bruzzese liked the senator's directness.

"When he said there were some things he couldn't get done, I thought, he's not making false promises about everything," said Ms. Bruzzese, 44, of Aliquippa.

But her friend, Rebecca Schepis, 47, of Sharpsburg, found herself still hungry for more information. A self-employed contractor, she pays more than $400 a month for health insurance and wondered how he would ease that particular financial burden for her -- and her parents.

Ms. Schepis' mother is on a fixed income, she said, "and waits for medicine samples rather than take medication every day, and she and my father aren't poor. They're middle-class people who can't afford to pay for the cost of drugs, so how is Obama going to make it happen for us?"

Mr. Obama's health plan -- which, unlike Mrs. Clinton's, is neither universal nor mandatory -- appealed to Trudy Nottingham, 53, of Wampum. A registered nurse, she finds Mrs. Clinton's approach unrealistic.

"I think she's a smart lady, but she wants everyone to buy insurance. People can't afford to do that, so how is that a solution?"

Her son Ian, who turned 18 last Friday, said he was leaning toward Mr. Obama for the same reason. He hopes to make a career in occupational therapy and "the health care situation is just terrible right now."

Ultimately, many in the crowd seemed to find Mr. Obama impressive in his first appearance here.

But for a few, he didn't make the sale.

"I'm still going to vote for Hillary Clinton," Ms. Schepis said after the senator departed for his next campaign event in Scranton, noting that it was time the country had a woman for president.

"The woman thing is an issue for me, and I believe in the Clinton policies from the past. She supported a lot of things her husband did, and it was not a bad eight years."

Ms. Bruzzese, who works for a transportation company, said she is torn between Mr. Obama and Mrs. Clinton.

"I'd give him five stars if this were a movie," she said. "He was really good. But I can't help it. I like them both. It's so hard to decide."

Ms. Gilbert is not having the same difficulty.

While she likes Mrs. Clinton, the New York senator is too much "a part of the status quo, while Barack continually says we don't want business as usual."

The possibility that Mr. Obama may become this country's first black president still trumps everything for Ms. Gilbert, who is black.

"You know, this is a once in a lifetime thing, for me to live and see an African American as a candidate for president," said Ms. Gilbert.

"Just the fact that he has come to this point, knowing where this country has been, is significant. I pray that he wins, and I think this is his time, because God has allowed him to get this far."