Add this to the list of headaches Microsoft is facing over its much-maligned Windows Vista operating system.  A woman is now suing the company for a $59.25 charge she incurred for downgrading her Lenovo computer from Windows Vista to Windows XP Professional. The class action suit, which was filed in U.S. District Court in Seattle Wednesday, alleges that Microsoft violated the state's Unfair Business Practices Act and the Consumer Protection Act. [PDF, 13 pages]

The suit, brought by Emma Alvarado of Los Angeles County, notes that consumers have encountered "numerous problems" with Vista that have been widely reported in media outlets.

(See Microsoft's response in update below.)

"As a result, many consumers would prefer to purchase a new computer pre-installed with the Windows XP operating system or at least not pre-installed with the Vista operating system," the suit says. "However, Microsoft has used its market power to take advantage of consumer demand for the Windows XP operating system by requiring consumers to purchase computers pre-installed with the Vista operating system and to pay additional sums to “downgrade” to the Windows XP operating system."

The suit --  first reported by the Seattle Post-Intelligencer -- alleges that plaintiffs have been damaged by Microsoft's monopoly power and anti-competitive business practices 'because they have been, and continue to be, forced to pay supra-competitive prices for Windows XP."

"That is, they have been forced to pay substantially more to acquire the Windows XP operating system than they would have to pay in a competitive marketplace in which there were available alternative operating systems," according to the lawsuit.

The suit also alleges that Microsoft used its monopoly power for Intel-based computers "to coerce OEMs, internet access providers
and others into agreeing to restrictive and anti-competitive licensing terms for its Windows XP operating system in order to stifle competition in the market."

Update: Here's Microsoft's statement on the lawsuit, via spokesman David Bowermaster.

"Microsoft does not have a downgrade program.  It does offer downgrade rights as part of some Windows Vista licenses, including Windows Vista Business purchased through the OEM channel.  Microsoft does not charge or receive any additional royalty if a customer exercises those rights.  Some customers may choose or need to obtain media or installation services from third parties to install the downgrade version."