Microsoft has released Windows Vista SP1 RC to the public today. You can download it through Windows Update or as a complete package from Microsoft Download Center. SP1 contains changes focused on addressing specific reliability and performance issues, supporting new types of hardware, and adding support for several new technologies. SP1 also addresses some management, deployment, and support challenges. Microsoft has also published documents on how SP1 will affect Vista performance and what are the changes it brings to its operation.
If you have a prior version of SP1 Beta installed, you will have to uninstall it prior to installing RC. Windows Vista SP1 RC will no longer operate after June 30, 2008 and should be uninstalled prior to that date.
Complete list of changes in Windows Vista SP1 RC
Did you try SP1 RC ?