Just a quickie

I am trying to see how long it takes to do something

the way I am checking to see if the time elapsed is less then a second is this, but it never seems to exit the loop:

Code:
while (DateTime.Now.Millisecond < 1000)
{
   this.lstMsgs.Items.Add(DateTime.Now.Millisecond.ToString());
}
this.lstMsgs.Items.Add("1 sec up");
it never seems to exit the loop.

any ideas?