From the blurb:
During the development of Windows Vista, several key investments were made to vastly improve overall quality, security, and reliability from previous versions of Windows. While we have made tremendous investments in Windows Vista to ensure backwards compatibility, some of the system enhancements, such as User Account Control, changes to the networking stack, and the new graphics model, make Windows Vista behave differently from previous versions of Windows. These investments impact Visual Studio 2005. The Visual Studio 2005 Service Pack 1 Update for Windows Vista Beta addresses areas of Visual Studio impacted by Vista enhancements. Many of the Windows Vista enhancements are documented at the Windows Vista Development Center.
The update is here.