how to synchronize time in windows 7

http://technet.microsoft.com/en-us/library/cc758905(WS.10).aspx

Administrative Credentials
To perform this procedure, you must be a member of the Administrators group on the local computer. To perform this procedure from a remote computer, you must be a member of the Domain Admins group.

To configure a client computer for automatic domain time synchronization

1. Open a Command Prompt.
2. Type the following command and then press ENTER:
   w32tm /config /syncfromflags:domhier /update
3. Type the following command and then press ENTER:
   net stop w32time
4. Type the following command and then press ENTER:
   net start w32time