Like a divorcing couple, estranged partners Hewlett-Packard Co. and Oracle Corp. are preparing to air their grievances in court.

Jury selection begins Thursday in a trial between the once cozy Silicon Valley giants who have degenerated into bitter rivals in the last two years. The trial, which will unfold in Santa Clara County Superior Court in San Jose, Calif., is to settle a dispute over a software contract.

At issue, at least nominally, is Oracle's decision last year to stop making its database software for some H-P server systems. The move, which involves H-P servers that use Intel Corp.'s Itanium processors, sparked a war of words and lawsuits between Oracle and H-P. Now H-P is going to trial to try to force Oracle to keep making software for the Itanium servers.

Even as the two companies go back-and-forth over the arcane technology, both sides have treated the run-up to the trial as an opportunity to publicly knock the other.

For more than a year, Oracle has waged a campaign that has undermined H-P's Itanium servers. Earlier this month, Oracle posted some internal H-P documents on its website and issued a news release encouraging H-P customers to read them 'so you can make your own decision regarding your investments in Itanium technology.'

The documents, most of which are several years old, paint a grim picture of the state of the Itanium products. They include emails in which an H-P executive discusses payments the company made to Intel to prop up the Itanium processor and his opinion that the poor future of the products is 'one of our most closely guarded secrets.'

H-P said it remains committed to Itanium servers and that this will become clear at trial.

H-P, for its part, is trying to paint Oracle as trying to hurt H-P at the expense of Oracle's customers and the befuddlement of the company's rank and file. 'We're going to f -- HP,' one Oracle executive said in an instant message released by H-P.

All of the sparring has appeared to exasperate even the judge in the case, James Kleinberg. In a pretrial hearing this month, Mr. Kleinberg likened the case to a 'divorce' and lamented he couldn't send the companies to family court, according to people who were there.

Some widely known names in Silicon Valley could take the stand as witnesses. They include Oracle Chief Executive Larry Ellison and Oracle co-president Mark Hurd, who was ousted as H-P CEO in 2010. Intel CEO Paul Otellini may also appear, though current H-P CEO Meg Whitman isn't expected to testify as she joined the company after the events in question.