Microsoft on Tuesday made the pre-Release Candidate 1 (RC1) of Windows Vista available for public downloading, saying that it wanted the extra testers to help track down bugs.

The not-quite-RC1, which debuted to a closed circle of testers last week, will be on the Microsoft site for a limited time: once 100,000 have downloaded the 3.2GB file, the Redmond, Wash. developer will shut off the spigot.

"Our goal in offering this build publicly is to help identify and track issues before RC1 is designated for release," wrote Nick White, a Vista product manager, on the group's blog. "Despite being so close to the actual release date of RC1, the download, installation, and usage feedback you send us on this build is still extremely important, otherwise, we'd not be spending resources on this interim build."

The pre-RC1 offering lends credence to reports that the actual RC1 build will release soon, perhaps within a week.

When the preview landed in some testers' hands Aug. 24, JupiterResearch analyst Joe Wilcox noted that IE 7 and Vista development have tracked together throughout the year. "Looking back, major IE 7 builds preceded new Windows Vista builds by no more than a week or two," Wilcox wrote on his blog last week. "So my expectation is that IE 7 RC1's release foreshadows that Windows Vista Release Candidate 1's release is imminent."

The 32-bit version of the pre-RC1 build of Windows Vista can be downloaded from this Microsoft Web site using either Internet Explorer or an alternate browser such as Firefox. As with other large downloads, the Vista build is an .iso file. To install the pre-RC1, users must burn the .iso file to a DVD.