There are two different ways that you can synchronize your time on a Unix machine. One way is a daemon that runs and constantly checks remote time servers for the current time, modifying the local clock frequently. Another is a simple program that just checks once and sets the time.

I think that the first is overkill for a system that isn't likely to be up for a long period of time. The second is pretty easy. Just get an ntpdate binary and have it run upon boot. It should be pretty easy to check to see if the network is up by searching the output of 'ifconfig eth0' for 'UP'.