As he steeled for battle in the courts, McBride brought in lawyer Boies, who won the government's antitrust suit against Microsoft, to see whether it could sue Linux users. His firm, Boies Schiller & Flexner LP, and other law firms associated with the case have received $1 million in cash and 400,000 SCO shares.

By March last year, SCO had sued IBM, and on May 14, less than a year after announcing the collaboration on a standard Linux program, SCO stopped selling its Linux products.

"The lawsuit has touched a nerve with a community of people who work very, very hard for something they believe very deeply in," said John Palfrey, executive director of Harvard Law School's Berkman Center for Internet and Society. "These are people who take what they do extraordinarily seriously."

SCO, then known as Caldera Systems, first sold shares to the public in March 2000. They doubled on their first day of trading, giving the company a market value of $1.1 billion as investors bet the company would benefit from Linux.

SCO didn't turn a profit until it started its crusade against Linux last year. It had $17.9 million in revenue and net income of $5.43 million in 2003. SCO said last week its first-quarter loss widened to $1.5 million on sales of $11.4 million.

SCO will have a difficult time proving its case, especially facing an adversary such as IBM, said James Pooley, a partner at Milbank, Tweed, Hadley & McCloy in Palo Alto, Calif. IBM, based in Armonk, N.Y., has as many attorneys specializing in intellectual property as there are private law firms in the field.

"Suing IBM is not something that should be taken on by the faint of heart," said Pooley, who has litigated in cases with and against IBM. "IBM has the resources and the track record for fighting for its positions."

Shares of SCO rose more than tenfold last year as investors bet the company would profit from the IBM lawsuit. The shares have declined 32 percent this year.

Former SCO Chief Executive Ransom Love, who hired McBride in June 2002, wasn't among the buyers. Love said he sold all his SCO shares after the company filed suit against IBM.

"It's tragic," Love said in an interview. "A company that helped build that whole industry has now turned against it."