I just purchased the kit and was looking at the parts list (schematic
will come later, i'm at work right now) and found it a little
disconcerting that there isn't a 32.768khz crystal (i.e. 1/2 second
for a 16-bit register). This frequency of crystal makes it
tremendously easier to build something that keeps time. Also, since
they are relatively slow, they can be pretty accurate, even for a
cheap one. Otherwise, you are at the mercy of either the internal
oscillator of the uC, or in this case, the 16mhz external oscillator.
It is not uncommon for these things to float a LOT (even though they
say this one is 50ppm, according to Mouser) due to temperature and
other environmental things, which would make a time system based on it
float also.

Unless I am missing something, which I very well could be.

--Daniel