For those who have been have been anxious to get their hands on the first release candidate of Windows Vista Service Pack 1, the time has finally come as Microsoft today began distributing the package through its Windows Update system.

SP1 brings numerous bug fixes and reliability updates that directly address customer complaints, including one of the most common: slow file copying. In fact, Microsoft is now promising 25% to 50% faster file copying operations. Further details about changes and additions in this update are available in Microsoft’s final change log for Windows Vista Service Pack 1.

To get the update, you first need to download and run a script so that Windows Update will detect your system configuration and offer some prerequisite packages before actually sending the RC1 to you – it may require as many as three updates before SP1 can be installed. So if you’re one who enjoys testing out early software releases, you can get started here.