Microsoft has launched the first public beta of Windows Vista Service Pack 2 (SP2). The company had already seeded the update to subscribers of its TechNet and Microsoft Developer Network (MSDN) services, and has now announced it would open the beta to anyone interested in trying the preview release.

Vista SP2 is now available in five language-specific editions: English, French, German, Japanese and Spanish. According to a Microsoft spokeswoman, the company won't be issuing the beta in any other languages; instead, 31 additional versions will be available only when SP2 reaches "release to manufacturing," or RTM, status.

Microsoft has not committed to Vista SP2 delivery or RTM dates, but TechARP, a website that has a solid track record of predicting such things said the update would hit RTM in April 2009.

Vista SP2 can be downloaded as a 388MB standalone installer for 32-bit versions or as a 614MB download for 64-bit. A 1.2GB .iso disk image is also available from Microsoft's website.

Users can also retrieve and install SP2 through Windows Update, Microsoft's default update service. Although Microsoft claimed that SP2 weighed in at only about 41MB as a Windows Update download (approximately 60MB for the 64-bit edition), Computerworld 's 32-bit downloads via Windows Update tipped the scales at 297MB.

But users must jump through some hoops before they can grab Vista SP2 from Windows Update, Microsoft warned in a document that spells out the process. First, they must download and save a short command script, then rename and run it with administrator privileges. The script, said Microsoft, will "set a registry key on your computer that will enable Windows Update to offer you the Service Pack."

With that hack out of the way, users must next download and install a pre-SP2 "Servicing Stack" update that lets Vista's installer handle the service pack. Another refresh of Windows Update should offer up Vista SP2, which can then be downloaded and installed. The latter may take as long as an hour, Microsoft noted in an on-screen message.

As is its usual practice, Microsoft set a time limit on the beta of Vista SP2, although it gave conflicting dates. In the instructions that walk users through the Windows Update process, it said the beta "will not longer operate after 1May 2010, and should be uninstalled prior to that date." The end-user licensing agreement (EULA) that pops up just prior to the actual installation, however, listed June 1, 2010 as the cut-off.

Microsoft did not immediately respond to a call for clarification on the beta's retirement date.

More information about the Vista SP2 beta, including links to downloads, release notes and the only available support option -- online forums -- can be found on Microsoft's TechNet and MSDN sites.
Vista SP2 contains all the hotfixes and security patches Microsoft issued from the time it wrapped up SP1 through October 2008, as well as a number of feature additions and improvements, including better power management, Windows Search 4 and Blu-ray data recording.