If you are not satisfied with the standard MS Windows features on time synchronization and want something more, try DNetTime. You can use more time-servers in order of priority. You can specify the download period. Besides using the single user downloading an application can work as a Windows service and perform the periodic download even when nobody is logged in the system.
The program supports command line and can therefore be used for your own application and specific requirements, such as time synchronization without interaction with the user.
