I use GPOs, under the "computer Configuration\Administrative Templates\System\Windows Time Service", to ensure that the time on the local computers sync with the DC. I direct all time to the server, then direct the server to an outside NTP server. Works extremely well with 400 computers over a WAN. I'm sure it'll work as well with a small network.
Technet procedure can be found here
If you are not familiar with using GPO's, Download the Group Policy Management Console