Local time box shows the time reported by your PC.
Atomic time shows the time value
reported by the atomic clock (or other server).
Difference window displays how far off
your PC is from the time server.
The Get now! button will cause the
application to get new time from the time server and compare it to
your local PC time.
The Adjust button will set your PC
clock to match the time server (taking into account your time zone
or hour offset, of course).
"Auto Adjust" section
Adjust on startup - auto adjust system time on
startup.
Hours Correction - turn this
option on if you want to correct time at the top of the hour.
You can also use the Synchronize and
exit option. It will remove Absolute Time Corrector from the
computer's memory after the clock synchronization.
Adjust when connection is established
mode means that ATC will automatically synchronize the clock every
time your computer establishes a dial-up connection.
Adjust every option. Set
your preferred update interval in the appropriate box.