Vista relies on Restart Manager to stop and restart applications during installation as opposed to requiring users to close applications manually. This minimizes the need for system restarts to upgrade files that may be in use. When a restart is needed, Restart Manager captures the state of the system including any open applications, files, or unsaved work. It then restores this state after the installation is complete, thereby ensuring that the running applications do not affect the installation with minimal impact on the user.

For more information on Restart Manager, visit http://msdn2.microsoft.com/en-us/library/aa372466.aspx

By now I’m sure you know that User Account Control (UAC) is the new security feature of Windows Vista which allows users to run with standard user privileges, even if you are logged in with an administrative account. Then when you try to perform an action that requires administrative privileges, UAC requests authorization from the user. Now we can rely on Windows Installer v4 to install all applications as managed applications (automatically installed with elevated privileges). Once an application is registered as a managed application, it no longer prompts for authorization during installation. Of course those applications that are not registered as managed will still see the usual UAC prompt (which as a standard user, requires admin credentials to be entered).

It can also patch applications without requiring elevated privileges, but to pull this off there are several conditions that must be met. Most notably, it must be digitally signed. Among the other requirements are that the application has to have been installed for all users (or per machine). I won’t go into all that is required here, but the bottom line is that when patches are properly prepared for Vista, they will install under standard user privileges without prompting.

For more information on patching with UAC, visit http://msdn2.microsoft.com/en-us/library/aa372388.aspx