On Thursday Microsoft asked a federal judge to dismiss claims of plaintiffs in the class-action lawsuit concerning their ‘Vista Capable/Ready’ marketing program from early 2007.

In 2006 Microsoft Executives went ahead with a plan to clear PC makers to denote computers as “Vista Capable” even if they could only run the stripped-down Vista Home Basic version of the OS.

Plaintiffs claim that the by program Microsoft breached the Washington Consumer Protection Act and gained illicit money because the false designation drove up computer demand and therefore prices.

Microsoft in its Thursday filing rebukes those claims and moves to have the class decertified. "Because it is clear that Plaintiffs cannot prove any element of their 'price inflation' theory, Microsoft moves for summary judgment," Microsoft's filing reads.

The filing attacked the main point of the plaintiffs’ argument, that Vista Basic was not vista due to lack of certain features like the Aero interface.

"The fact that Windows Vista Home Basic lacks some features available in premium editions of Windows Vista (as Microsoft always disclosed) shows only that Microsoft properly markets Windows Vista Home Basic as a distinct budget edition," replied Microsoft's attorneys. "Windows Vista Home Basic falls well within the Windows Vista family as a technical matter."

Microsoft lawyers also said that plaintiffs were unable to prove that Microsoft gained any undue revenue from Vista sales.

It all now rests in the hands of Judge Marsha Perchman, who certified the class action in February. While she denied plaintiffs’ original claims that Microsoft deceived users into buying PCs which they wouldn’t have bought otherwise, she let them argue that Microsoft had illegally raised prices.

If she dismisses these claims as well, it’s all over for the case which drew a lot of public attention and a number of internal emails into the open, including some that have shown Microsoft had been under pressure from Intel to lower requirements for PCs to receive the “Vista Capable” tag.