Using local security settings, I added Change System Time to the
limited user.
I will just pretend you are talking about XP Pro SP3.
Limited user accounts cannot change the time.
If you adjust the Local Security Policy and add that Limited user to
the Change the system time policy, they can change the time, but the
Internet Time tab of the Data and Time Properties dialog box are
unavailable (greyed out).
That is they way it works, but I believe there are some third party
programs to mimic the XP Internet Settings sync function so you could
install one of them and give your limited user the ability to run it
and it includes a time sync option. XP won't let you, but this other
program might.
Never tried it and can't experiment right now, but here is one I read
about from a Google search:
http://www.filebuzz.com/fileinfo/31814/FG_Time_Sync.html
The account is called Limited for a reason.