JavaScripting to find the difference between dates in hours, minutes, & seconds

Here's another little bit of JavaScript that I've found handy recently. It will calculate the difference between two dates and present the results in days, hours, and minutes. For the purposes of this post, I'm using today and Christmas day as the days that I'm trying to find the difference between.

 var today = new Date();
 var Christmas = new Date("12-25-2009");
 var diffMs = (Christmas - today); // milliseconds between now & Christmas
 var diffDays = Math.round(diffMs / 86400000); // days
 var diffHrs = Math.round((diffMs % 86400000) / 3600000); // hours
 var diffMins = Math.round(((diffMs % 86400000) % 3600000) / 60000); // minutes
 alert(diffDays + " days, " + diffHrs + " hours, " + diffMins + " minutes until Christmas 2009 =)");