NOTE:  The countdown clock reads the date and time from your computer's clock.  This means that the countdown clock displayed above is only as accurate as the settings on your clock.

You will need to synchronize your clock periodically due to the tendency of computer clocks to drift by several seconds or even minutes over a short period of time.

There are also some great programs available which allow your computer to automatically synchronize with a remote time server (like the US Naval Observatory time server).  Search the Internet for "time synchronization software" and you'll surprosed at how much free or very cheap software is available to do this job!