Ramblings from another nerd on the grid
Ready to begin testing Windows Vista for real now? Good!!! The Server Pack 1 Release Candidate 1 is now available to the public. There are several ways to get it.
Get Windows Vista Service Pack 1 RC (Update for existing Windows Vista users)
There are 3 different ways to access the Windows Vista SP1 RC depending on the unique business needs of individual users and their organizations.
Be sure to read all the details at http://technet.microsoft.com/en-us/windowsvista/bb738089.aspx before you do anything. And please make a backup before you start the install process.