Countdown Clock - Convert Resulting Milliseconds To Back To Time Format ?

teaching myself javascript. my current self-challenge is to write a countdown clock that will tick off the days, hours, minutes, seconds until a certain date.i'm thinking that this should be what's happening in the javascript:

get current date/time (using new Date())

get future date/time counting down to (using new Date(2009,7,7))

subtract current from future (Math.ceil(movie.getTime - today.getTime))

convert resulting milliseconds to back to time format (not sure how to do that yet)write result back to html page (not sure how to do that yet, either)loop the whole thing every 1000 milliseconds.is this a workable idea? it seems the most straightforward way of doing it, but other scripts i've found on the web seem much more complicated.