Lawyers for Microsoft and PC users are set to square off in a federal courtroom tomorrow as the Redmond company tries to end the class-action lawsuit over the company's "Windows Vista Capable" marketing program.

The lawsuit so far has revealed large volumes of internal Microsoft emails, starting with a series of messages in which Microsoft executives complained privately about their own problems with Windows Vista. More recently, the emails have shown how Microsoft lowered the requirements for the Vista Capable designation to help Intel avoid losing billions of dollars -- ticking off HP and others in the process.

In other words, the case hasn't exactly been a public-relations boon for Microsoft, seemingly increasing its motivation to make it go away.

In court Thursday morning, U.S. District Judge Marsha Pechman in Seattle will hear arguments over Microsoft's requests for summary judgment and decertification of the class.

It's the first time Judge Pechman has scheduled oral arguments in the case since holding a class-certification hearing. Numerous motions and legal disagreements have come up in the case in the meantime, without courtroom hearings. It's not clear why the judge scheduled arguments in this situation, or what that might say about which way she's leaning on the issue.

The "Vista Capable" logos were used by Microsoft and PC makers in late 2006 to assure holiday PC shoppers that the computers they were buying would run the delayed operating system when it came out in early 2007. The lawsuit alleges that the "Windows Vista Capable" designation was wrongly given to PCs that couldn't run Vista's signature features, such as the Aero Glass interface.

Microsoft filed its motions for summary judgment and class decertification in November, saying the plaintiffs hadn't proven their remaining legal arguments. Those arguments include a contention that the program artificially inflated demand for, and prices of, the PCs alleged to have been wrongly given the "Vista Capable" designation.

Each side will have 30 minutes to present its case starting at 10 a.m. tomorrow. We'll be at the courthouse, so check back for coverage.