In their last opportunity to sway the federal judge conducting the Microsoft Corp. antitrust trial, attorneys for the government yesterday cast the software giant as a monopolist that has squelched competition in the computer industry, while the company's legal team accused the government of needlessly meddling in the rough-and-tumble world of technology.

After a lengthy summer break, the lawyers returned to court yesterday--more than 11 months after the historic trial began--to present often-passionate closing arguments that were replete with pointed rhetorical barbs, excerpts from internal Microsoft e-mail and, in the government's presentation, clips of the unflattering videotaped deposition of the company's billionaire chairman, Bill Gates.

Microsoft's actions have "cost consumers untold millions, probably hundreds of millions, of dollars," argued Stephen Houck of the New York attorney general's office. The evidence, he said, "leaves no doubt that Microsoft's illegal behavior has been bad--very bad--for consumers."

Microsoft's lead attorney, John L. Warden, acknowledged that the firm has been an aggressive competitor but he maintained that it has broken no laws. "Large companies often take tough stances with one another in business negotiations, but that doesn't mean they need the government, in the guise of antitrust enforcement, to act as some sort of hall monitor," he said.

The judge, Thomas Penfield Jackson, is expected to issue a preliminary ruling in several weeks that will outline the facts he believes each side has proved. Jackson likely will issue a final ruling several months later.

During yesterday's proceedings, Jackson appeared to intently follow the lawyers' presentations, but he did not ask any questions or provide any other indications of how he intends to rule.

Legal analysts believe the two-step process is designed to encourage the lawyers to reach an out-of-court settlement. Although the two sides have held exploratory meetings, sources familiar with the matter said they remain far apart.

Should the government win, Houck suggested publicly for the first time that the states would support a breakup or some other fundamental restructuring of Microsoft. "If the market remains structured as it currently is now, Microsoft will have both the means and the incentive to do what it has done for many years--to restrict consumers, to raise prices and to stifle innovation," he said.

The Justice Department and 19 states allege that Microsoft has bullied and threatened competitors in an effort to maintain a monopoly with its Windows operating system software for personal computers. The government also contends that Microsoft has tried to monopolize the market for Internet browsing software and has engaged in business deals that illegally restrain trade.

"This is a monopolist who has been very vigilant in protecting its monopoly power," said David Boies, the Justice Department's lead attorney.

Boies, a normally dramatic courtroom presence, delivered a more muted performance yesterday. He read from an outline that was displayed on two large projection screens before taking the judge on a hour-long tour of dozens of e-mail messages that were introduced as evidence.

Boies spent much of the time reiterating the government's central contention: Microsoft added its Internet Explorer browser to Windows in an effort not to help consumers but to crush rival Netscape Communications Corp. Microsoft worried that Netscape's browser could serve as a "platform" for software products, creating a potent new rival to its flagship Windows product, the government contends.

Boies argued that Microsoft first tried to urge Netscape not to make a browser for the Windows operating system. When Netscape refused, he said, Microsoft embarked on a predatory campaign by "bundling" its browser in Windows.

Microsoft's Warden took issue with each point raised by Boies. He said the notes taken by former Netscape executive Marc Andreessen, which outline Microsoft's alleged efforts to divide the browser market, were "cooked in some fashion."

Warden said Microsoft decided to include its browser in Windows and give it away for free before Netscape was formed in 1995. He called the government's contention "a chronological impossibility."

His presentation was peppered with barbs at the government. He called a contention made by the government chief economic witness "pure baloney." Then he displayed a sheet of blank graph paper on the projection screen, telling the judge that it was the analysis the economist conducted.

Warden spent the bulk of his time arguing that Microsoft does not have a monopoly, saying that any one of many new technologies, from the rival Linux operating system to Internet-based software applications, could quickly threaten the dominance of Windows.

At the end of the day, after hearing from each side for 2 1/2 hours, Jackson stood up and said simply: "The matter is submitted."