Who knew you could easily setup a NTP server on your Windows 2008 R2 box without installing third party software? By tweaking some registry keys, setting a service to automatic startup and grabbing a cup of coffee for the work done you have the NTP server running in a moment!

1. Click Start, click Run, type regedit, and then click OK.
2. Locate and then click the following registry entry: HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesW32TimeConfig
3. In the right pane, right-click AnnounceFlags, and then click Modify.
4. In the Edit DWORD Value dialog box, under Value data, type 5, and then click OK.
5. Enable NTPServer.
   1. Locate and then click the following registry subkey:
      HKEY_LOCAL_MACHINESYSTEMCurrentControlSet
      ServicesW32TimeTimeProvidersNtpServer
   2. In the right pane, right-click Enabled, and then click Modify.
   3. In the Edit DWORD Value dialog box, type 1 under Value data, and then click OK.
6. Exit Registry Editor.
7. At the command prompt, type the following command to restart the Windows Time service, and then press ENTER: net stop w32time && net start w32time

Afterwards change the service “Windows Time” by setting it to startup automatic.

Done! Now enjoy your cup ‘o coffee =)

(Instructions used from: http://bchavez.bitarmory.com/archive/2009/12/21/how-to-setup-a-windows-2008-r2-sntp-ntp-server.aspx Thanks to Brian Chavez!)