Countdown Timer

hello people, I want create Countdown Timer in my page which will be great for counting down to "relative" events such as Christmas, birthdays....
what is the simplest way to do that please?

thanks in advance

 

maybe a little java script, i found this one, simple but it works and is editable.
http://www.hashemian.com/tools/javascript-countdown.htm

 

perfect ! exactly what I need .. thanks a lot