Justin Ho

Select a time source:

Stratum 2: https://support.ntp.org/bin/view/Servers/StratumTwoTimeServers
Pool: https://support.ntp.org/bin/view/Servers/NTPPoolServers
I've used pool.ntp.org and an NRC server in Canada below.

Standalone machine:

w32tm /config /syncfromflags:manual /manualpeerlist:"pool.ntp.org time.nrc.ca"
w32tm /config /update
net stop w32time
net start w32time

Note the lack of space between manualpeerlist, the : and the ".

Domain configuration:

1. Configure PDC emulator to sync to external time source [1]:
   
   w32tm /config /manualpeerlist:"pool.ntp.org time.nrc.ca" /reliable:yes /update
    
2. If you move the role of the PDC emulator to a new domain controller, Change the Windows Time service configuration on the previous PDC emulator [2].
   
   w32tm /config /syncfromflags:domhier /reliable:no /update
net stop w32time
net start w32time
 
3. Configure a client computer for automatic domain time synchronization [3]:
   
   w32tm /config /syncfromflags:domhier /update
net stop w32time
net start w32time

Further reading:
Windows Time Service Tools and Settings
http://technet.microsoft.com/en-us/library/cc773263(WS.10).aspx

Good overview - explains domain hierarchy and time architecture
http://blogs.msdn.com/w32time/archive/2007/09/04/keeping-the-domain-on-time.aspx

Configuring a time source for the forest
http://technet.microsoft.com/en-us/library/cc784800(WS.10).aspx

How to synchronize the time with the Windows Time service in Windows XP
http://support.microsoft.com/kb/307897

Sources:

[1] http://technet.microsoft.com/en-us/library/cc786897(WS.10).aspx via http://go.microsoft.com/fwlink/?LinkId=91969
[2] http://technet.microsoft.com/en-us/library/cc738042(WS.10).aspx  
[3] http://technet.microsoft.com/en-us/library/cc758905(WS.10).aspx via http://go.microsoft.com/fwlink/?LinkId=91376