In a post on the official Windows Vista blog, Microsoft announced the release candidate of Windows Vista SP1 is available via Microsoft Connect. Also the users who are interested to try the new update will have to wait until next week, when the Vista SP1 RC will be available will be available to the public.

According to Microsoft, Windows Vista SP1 will not add new features, but instead it will address key feedback received from its customers. In addition, the company insisted that the SP1 would not affect any applications that are currently running on Windows Vista.

Amongst other things Vista SP1 will enhance BitLocker Drive Encryption (BDE) by offering an additional multifactor authentication method that combines a key protected by the Trusted Platform Module (TPM) with a Startup key stored on a USB storage device and a user-generated personal identification number (PIN).

In addition, the update will add support for upcoming standards and hardware, such as Direct3D 10.1, Secure Sockets Tunneling Protocol (SSTP), Extensible Firmware Interface (EFI), and the Extended File Allocation Table (exFAT), a file system for Flash drives.

The service pack will include support for Secure Digital (SD) Advanced Direct Memory Access (DMA), which will be on compliant SD host controllers soon, to improve transfer performance and decrease CPU utilization.

According to Windows Vista blog, the Release Candidate contains several changes over the Beta release version.

For example, the size of the standalone installers has decreased significantly. The standalone installer packages consisting of just the five languages (again, x86 and x64) slated for initial release are more than 30% smaller. Previous SP1 versions left behind a directory of files that was not needed after installation and occupied about 1GB of space; the RC includes automatic disk clean-up to remove this directory.

The amount of hardware space required to install SP1 has also been reduced. A 32-bit version of the beta had required 7GB of space. That is now down to about 4.5GB, depending on the system configuration,

Earlier today Microsoft announced morning that it would withdraw an anti-piracy tool from Windows Vista, which disabled most the operating system if it considered that a user did not pay for a copy of the software.

Known as “Kill Switch”, the tool was especially designed to prevent users with illegal copies of Vista from using certain features.

The new update will help the users to install their legal copy of Windows Vista without having the same problems as before. In case they have an illegal copy of Windows Vista users will get pop up messages, which notify them about the status of the software along with information about how to make the software legal. Still the Release Candidate will not include this feature.

Microsoft confirmed that it is on track to deliver the Windows Vista SP1 in the first quarter of 2008 as promised.