Microsoft has set pricing for the Windows Vista operating system for the US market, although UK and rest of the world pricing is not yet available.

The Redmond-based company also confirmed again its commitment to releasing the OS in January, after distributing it to business customers in November.

The upgrade price for those with older versions of Windows is set at between $100 to $259, depending on which version required. The most expensive will be the “ultimate” edition, designed for business users.

The standalone products will cost from $199 to $399.

The most popular consumer version of Vista is expected to be the Home Premium edition, which features in-built entertainment options, like support for HD TV and DVD editing and burning, and will cost $159 for the upgrade from older Windows.

Release Candidate 1, a test version of Vista, was made available to 5 million business customers worldwide to try out; feedback from users will ultimately determine if the system is ready for release in January.