Microsoft Corp. Tuesday quietly launched the release candidate of Windows Vista Service Pack 2 (SP2) to the general public, making good on a promise from last week.

Vista SP2 Release Candidate (RC) can be downloaded today from Microsoft's Web site in versions for both 32- and 64-bit systems.

As first reported by Neowin.net, while Microsoft has made Vista SP2 RC available to the public, it has yet to change the download pages' titles to reflect that the files are the release candidate and not Beta 2. The file name of the disk image, however, reveals that it is, in fact, the RC: 6002.16670.090130-1715_iso_update_sp_wave0-RCSP2.0_DVD.iso .

"This build is the same build sent out to select testers last week," Neowin said.

A week ago today, Microsoft announced it had wrapped up Vista SP2 RC, and had posted it to TechNet and MSDN (Microsoft Developer Network), the subscription-based services that cater to IT professionals and developers. At the time, a company spokeswoman said that the release candidate would be offered to everyone else this week.

Microsoft has not nailed down a ship date for SP2, and in the past has only said it plans to deliver final code during the second quarter of 2009.

Others, however, have pegged the release sooner rather than later. The Malaysian Web site TechARP.com, which has accurately predicted past Windows delivery dates, has said Vista SP2 is on track to launch no later than mid-May.

Users can download Vista SP2 RC as a standalone fresh installation disk image, as an update for the 32-bit version of Vista or as an update for the 64-bit version from Microsoft's site.

Although Microsoft will offer Vista SP2 SC through its Windows Update service -- as it did when it rolled out SP2 Beta 2 late last year -- it has not yet turned on that switch. Most people will use Windows Update to get SP2 RC, if only because downloads through the service will be significantly smaller, between 41MB and 90MB, as opposed to the 302-508MB of the files available now.

Machines must be running Vista SP1 to download and install the SP2 release candidate.