SALISBURY -- The timing couldn't have been better as Olympic swimmer Michael Phelps spoke Monday to soon-to-be graduates of Parkside High about the "hardest time of my life" -- his drunken driving arrest here last fall.

This is senior week at the Eastern Shore school. Friday is the prom, followed by the annual after-prom bash at the YMCA. Lots of parents, students and school officials are busy urging students to sign a Prom Pledge not to drink during the big weekend.

As if on cue, Phelps strolled onto the school's auditorium stage Monday morning, casually explaining how a loss of focus on his lifelong goals contributed to his decision to get behind the wheel of his 2005 Land Rover after drinking with two companions Nov. 4. He ran a stop sign and nearly sideswiped a police car.

"I'm here to talk about making good decisions, because I made a bad one that could have endangered myself or someone else's life," Phelps said. "I wasn't seeing the total picture. My true friends were not with me. If they had been, they'd never have let me in a car."

Phelps' appearances Monday at Parkside and two other schools helped to fulfill a plea bargain in which he pleaded guilty to driving while impaired, and prosecutors dropped a more serious charge.

As a part of his probation, Phelps agreed to talk to students at the three Wicomico County schools and to be a featured speaker at a "Healthy U" rally at Perdue Stadium in Salisbury this summer.

Dressed casually in jeans, flip- flops and a linen jacket, a hint of stubble on his chin, the 19-year-old swimmer -- who won eight medals at last year's Athens Olympics, including six golds -- could easily have passed for a Parkside senior.

"We're all pretty much the same age here," said Phelps, who is from Baltimore County's Rodgers Forge. "I was in the same situation you guys are in about two years ago -- getting ready for the senior prom. I remember that my friends were drinking, and I was the [designated driver]. I think I was able to save the lives of some of my best friends."

Phelps told students that many of his friends drank on weekends through high school and that he often took the car keys of drunken friends. "My mom always got the call that I'd be a little late because I was driving somebody home."

Stephen Abresch, one of five seniors who volunteered to talk to reporters after Phelps' appearance, said he thought it had been worthwhile.

"It's an exciting time in our lives, and it was basically a message that you can have fun in life, but you have to take responsibility for your decisions," said Abresch, 18.

Eighteen-year-old Megan Hurchalla, who plans to study communications at McDaniel College, said students were more likely to listen to Phelps than other speakers.

"He's a celebrity, he's our age and not some 30-year-old who came in to talk to us," she said.

Glancing occasionally at notes, Phelps was poised, speaking in a conversational style. He has become a familiar advertising pitchman who has endorsed a variety of products since his Olympic success.

David Elzey, who heads the Eastern Shore chapter of Mothers Against Drunk Driving, said he thought Phelps put students at ease.

"He has the capacity to reach out," said Elzey. "If they take him seriously, he could affect their lives."

In a tightly scripted visit, Phelps arrived at the school early, riding in a black sport util ity vehicle with tinted windows, chauffeured by Salisbury defense attorney James V. Anthenelli.

Phelps said he flew in Sunday from the University of Michigan, where he has enrolled in classes and is training with longtime coach Bob Bowman.

Recalling a recent interview with the cable sports network ESPN, Phelps said he was asked what one thing he would choose to change in his life. His arrest, Phelps said he replied.

"Remember that your decisions, good and bad, will be with you forever," he told students.