Yes and no. It will only occur automatically if the time server is a domain
controller. All XP boxes (and W2K workstations) will attempt to sync with a
domain controller with no particular action on your part (by default). The
standard routine is to use the command you mention on the domain controller
to get UTC sync from an outside source to the domain controller. Then,
nothing needs to be done to the workstations. All automatic.
If you are not using a domain controller for this, you will have to set each
client (using the command you reference) to sync to the server running the
time server.
Do NOT confuse this with the "net time /set \\computername" command.
Entirely different animal. The "net time /set \\computername" command DOES
NOT use the time service at all. It simply syncs time to whatever computer
name you insert. It is only a NetBIOS command, rather than the actual
Internet time service standardof sntp. The time service uses the standard
network time service protocol (sntp - "simple network time protocol") on UDP
port 123.
As far as how often sntp syncs, that is very complex. It can sync as often
as every hour or so, or, after stabilized, sync only every day or so. It
even makes drift corrections and syncs more often or less often depending on
how much drift occurs between specific syncs. You might want to read more
about it on the Microsoft site
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/randz/protocol/sntp.asp
It's been a while since I looked into this.
-Frank