Both versions work in exactly the same way, and I probably cut about a third of the code base so I'm quite happy with the result.
// create a new date and insert it
var myDate = new Date(2012,11,25,0,0,0)
Just include the JQuery file and call the $.countdown function. The function takes two arguments, a selector and a date object. The returned response will be written into the element you pass in as the selector.
You can view a demo below, or download the whole thing.
Download the JQuery Countdown plugin