NTPDATE Script

Hey guys I need help writing a script for a comupter to run locally.

The time on the computer for some reason runs slow so every 2-3 min it’s off by a lot.

Is it possible to write a script that could execute the following command every 2-3 min?

ntpdate time.apple.com

Or does anyone know a workaround for the time/clock preference to run more often it just does not seem to work on this computer running 10.4.8?