Stopwatch with Callback delegates

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace System {

    /// <summary>
    /// General stop watch with callback delegates
    /// </summary>
    public class StopWatch:IDisposable {
        public const string NUMBER_FORMAT = "#,#";
        //StopWatch.GlobalDurationCallBack += new Action<TimeSpan,string>((duration,name) => {
        //  //do something
        //});
        public static Action<TimeSpan,string> GlobalDurationCallBack { get; set; }

        #region Static Create()
        public static StopWatch Create() {
            return new StopWatch(GlobalDurationCallBack);
        }
        public static StopWatch Create(string name) {
            return new StopWatch(GlobalDurationCallBack) { Name = name };
        }
        public static StopWatch Create(string name,Action<TimeSpan,string> durationCallBack) {
            return new StopWatch(name,durationCallBack);
        }
        public static StopWatch Create(Action<TimeSpan,string> durationCallBack) {
            return new StopWatch(durationCallBack);
        }
        #endregion

        long _start;
        TimeSpan _duration;
        Action<TimeSpan,string> _durationCallBack;
        string _name;

        public string Name {
            get { return _name; }
            set { _name = value; }
        }
        public TimeSpan Duration {
            get { return _duration; }
        }

        #region ctr
        public StopWatch()
            : this(null,GlobalDurationCallBack,true) {
        }
        public StopWatch(string name)
            : this(name,GlobalDurationCallBack,true) {
        }
        public StopWatch(string name,Action<TimeSpan,string> durationCallBack)
            : this(name,durationCallBack,true) {
        }
        public StopWatch(Action<TimeSpan,string> durationCallBack)
            : this(null,durationCallBack,true) {
        }
        public StopWatch(Action<TimeSpan,string> durationCallBack,bool startStopWatch)
            : this(null,durationCallBack,startStopWatch) {
        }
        public StopWatch(bool startStopWatch)
            : this(null,GlobalDurationCallBack,startStopWatch) {
        }
        public StopWatch(string name,Action<TimeSpan,string> durationCallBack,bool startStopWatch) {
            _name = name;
            _durationCallBack = durationCallBack;

            Reset();
            if(startStopWatch)
                Start();
        }
        #endregion

        public void Reset() {
            _duration = TimeSpan.Zero;
            _start = 0;
        }
        public void Start() {
            Reset();
            _start = DateTime.Now.Ticks;
        }
        public TimeSpan Stop() {
            if(_duration == TimeSpan.Zero) {
                long end = DateTime.Now.Ticks;
                _duration = new TimeSpan(end - _start);
            }
            if(_durationCallBack != null)
                _durationCallBack(_duration,_name);
            return _duration;
        }
        public override string ToString() {
            return ToString(NUMBER_FORMAT);
        }
        public string ToString(string millisecondsFormat) {
            double totalMilliseconds = -1.0D;
            if(Duration != TimeSpan.Zero)
                totalMilliseconds = Duration.TotalMilliseconds;
            return totalMilliseconds.ToString(millisecondsFormat);
        }
        public void Dispose() {
            Stop();
        }
    }
}