An open-source group mocked Microsoft on a newly launched Web site dubbed BadVista.org and claimed the Windows operating system is a "power grab" to steal control over users' computers.

The Free Software Foundation's campaign will both promote free software alternatives to Vista and publicize what it sees as the danger of Microsoft's new operating system, the group said.

"Vista is an upsell masquerading as an upgrade," said John Sullivan, the group's program administrator, on the site. "It is a ruse to compel the further transfer of control over peoples' computers to an external and mysterious certification authority with peculiar standards of 'genuine.' It's a ploy to artificially motivate the purchase of expensive, unnecessary hardware."

In other entries on the BadVista.org site, Sullivan labeled Microsoft's Trusted Computing initiative as "Treacherous Computing," called the company's marketing campaign a "power grab," and promised to promote free operating system alternatives, especially Linux.

Some of Sullivan's Vista criticisms have been voiced before. Users have been up in arms for weeks over new anti-piracy technologies in Vista that will disable counterfeit copies, while research analysts have more recently said most existing hardware will need to be upgraded to take advantage of all of Vista's features.

Microsoft didn't immediately respond to a request for comment.