Internet Time Service
The Internet Time Service automatically synchronizes time on your Windows XP computer with Microsoft's time server time.windows.com. This server, in turn, synchronizes time with National Institute of Standards and Technology (NIST) computers, which synchronize with an atomic clock.
If your Windows XP computer is a standalone computer and is connected to the Internet, it will synchronize time automatically with time.windows.com every seven days by default, as shown in Figure 4. You will not be prompted to synchronize time manually. Whether you synchronize time automatically or manually, time is an important service, and it is best to ensure that your time is accurate on your computer. If you decide to turn off this feature, go to Control Panel, Date and Time. Then click on the Internet Time tab and uncheck the box Automatically Synchronize with an Internet Time Server.
Figure 4 Synchronizing time.
If your Windows XP computer has joined a domain, it will synchronize time with the time service on your domain controller. This cuts down on the traffic to the Internet. I don't recommend disabling this crucial service, but if you decide to disable time synchronization on your network, use the following procedure to modify the Group Policy:
Open the Group Policy that you want to configure.
Go to Computer Configuration, Administrative Templates, System, Windows Time Service, Time Providers.
In the right pane, double-click Enable Windows NTP Client, click Disabled, and then click OK.
In the right pane, double-click Configure Windows NTP Client, click Disabled, and then click OK.