What used to be called "Shared Computer Toolkit for Windows XP" has been updated to version 2.5, and has support for XP and Vista, but unfortunately remains 32-bit only. 64-bit support seems to be absent.
New to version 2.5:
Installation has been simplified and the improved Windows Disk Protection feature in Windows SteadyState does not require repartitioning.
The Windows SteadyState UI has been redesigned to help make common tasks easier to manage from one location.
With simplified user restriction settings, you can choose a High, Medium, or Low restriction level for each user account.
Windows SteadyState enables you to import and export user accounts from one computer to another.
Ongoing support efforts include a fully-revised Windows SteadyState Handbook (included in both PDF and XPS formats), updated Help content included with the download, new online demos, and the new Windows SteadyState Community Web site.
Increased Protection for All Users – Windows SteadyState includes more Windows and program feature restrictions, as well as support for Windows Update. Windows SteadyState also enables you to restrict user access to local programs.
You can download version 2.5 from here and read the Technical FAQ here.