Microsoft has made the Service Pack 2 release candidates of Windows Vista and Windows Server 2008 publicly available for download.

The prerelease software, which is for evaluation and testing, provides fixes for a number of reliability, performance, and compatibility issues. The service packs are available for download in 32- and 64-bit versions and require the system to be running SP1. Beta versions of the operating systems have to be removed before installation.

Among the changes in Vista are support for Blu-ray disc burning and Bluetooth 2.1. In addition, there's easier Wi-Fi setup and Windows Search 4.0, which improves indexing and search relevance. The server version includes a fully integrated Hyper-V virtualization environment and better management options.

At no additional charge, Hyper-V comes with one daughter OS with Windows Server 2008 Standard, four licenses with the enterprise edition, and an unlimited number of licenses with the data center version.

SP2 RC was released March 4 to select testers. The beta version has been around since October. While the fixes are a welcomed improvement, many users are more interested in the upgrade path to Windows 7, which is expected early next year.

Microsoft has said that anyone who buys a Vista PC after July 1 from a manufacturer participating in the software maker's upgrade program will get an upgrade to Windows 7 at no additional cost. Microsoft released Windows 7 in beta in January.

InformationWeek has published an in-depth report on Windows 7. Download the report here (registration required).