AN FRANCISCO, June 9 — Apple Computer plans to begin a nationwide print and television advertising campaign on Monday focusing on people who have switched to Apple's Macintosh from computers that use Microsoft's Windows operating system.

The series features individuals standing against a white background talking about how they felt after moving away from Windows. The statements are meant to be informal and personal, and one Macintosh convert likens using a Windows-based computer to "being stuck in a bad relationship."

The $50 million campaign was produced by TBWA/Chiat/Day and directed by Errol Morris, the documentary filmmaker who directed "The Thin Blue Line."

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Apple's co-founder and chief executive, Steven P. Jobs, said the company selected the people in the ads from more than 10,000 e-mail messages it had received as unsolicited testimonials.

"The most important thing for us is that viewers are smart about advertising," he said. "We've all had too many tobacco companies tell us they're good guys to believe advertising. We let these people speak for themselves."

He also said he did not think the ads would offend Microsoft, a company that has a relatively fragile relationship with Apple.

"Our relationship with Microsoft is really pretty good," Mr. Jobs said. "What's a few market-share points between friends? It wouldn't matter to them, and we would be eternally grateful."

He said the new campaign would be Apple's largest since the company's "Think Different" campaign, which began in 1998.