How Long Ago Did Something Happen

Hey, ive got a listof events that have occured on my site, updates etc. and Im trying to show how long ago the updates happened. For instance, say the date of an update is : 16/10/2007 15:16:03
 I want the Label to say "Happened over 2 months ago" etc.
Now ive tryed to use an IF statment but I cant seem to get it right :
        DateTime dt = Convert.ToDateTime("16/10/2007 15:16:03");

        if(dt.ToShortDateString() == DateTime.Now.ToShortDateString())
        {   //happened today
            if(dt.ToShortTimeString() == DateTime.Now.ToShortTimeString()||dt.ToShortTimeString() < DateTime.Now.AddMinutes(-1).ToShortTimeString())
            {   //happened within a minute
                UpdateLabel.Text = "About A Minute Ago";
            }
        }
        else if (dt.ToShortTimeString() == DateTime.Now.AddDays(-1).ToShortTimeString())
        {   //happened yesturday
            UpdateLabel.Text = "Updated Yesturday";
        }
        else if (dt.ToShortDateString() == DateTime.Now.ToShortDateString() || dt.ToShortDateString <= DateTime.Now.AddDays(-7).ToShortDateString())
        {
            UpdateLabel.Text = "Updated Last Week";
        }
Any ideas where Im going wrong? Im probally staring it straight in the face, but I cant see it. Thanks in advance John