Managed Machine Service user should be assigned these priviliges:

1. Included in the Backup Operators and Administrators groups.
2. Granted the Full Control permission on the folder %PROGRAMDATA%\Acronis (in Windows XP and Server 2003, %ALLUSERSPROFILE%\Application Data\Acronis) and on its subfolders.
3. Granted the Full Control permission on certain registry keys in the following key: HKEY_LOCAL_MACHINE\SOFTWARE\Acronis.
4. Assigned these user rights:
   • Log on as a service
   • Adjust memory quotas for a process
   • Replace a process level token
   • Modify firmware environment values

During installation, you can specify an existing user or create a new one. The specified user will be granted necessary rights during installation. In case you need to specify the rights manually (e.g. when changing the user later)