Dim objTmr As New System.Timers.Timer
    Protected Overrides Sub OnStart(ByVal args() As String)
        ' Add code here to start your service. This method should set things
        ' in motion so your service can do its work.
        objTmr.Interval = 1000 'One Second
        objTmr.Enabled = True 'Indicates whether the elapsed event is raised
        objTmr.AutoReset = True 'Indicates whether the event is fired each the interval elapses
        AddHandler objTmr.Elapsed, AddressOf objTmr_Elapsed
    End Sub

    Protected Overrides Sub OnStop()
        ' Add code here to perform any tear-down necessary to stop your service.
    End Sub

    Private Sub objTmr_Elapsed(ByVal sender As Object, ByVal e As System.Timers.ElapsedEventArgs)
        Dim objTime As New TimeSpan(12, 0, 0)
        If TimeSpan.Compare(DateTime.Now.TimeOfDay, objTime) >= 0 Then
            'Do your task here
        End If
    End Sub

System.Timers.Timer objTmr = new System.Timers.Timer(); 

protected override void OnStart(string[] args) 
{ 
 objTmr.Interval = 1000; 
 objTmr.Enabled = true; 
 objTmr.AutoReset = true; 
 objTmr.Elapsed += new System.Timers.ElapsedEventHandler(objTmr_Elapsed); 
} 

protected override void OnStop() 
{ 
} 

private void objTmr_Elapsed(object sender, System.Timers.ElapsedEventArgs e) 
{ 
 TimeSpan objTime = new TimeSpan(12, 0, 0); 
 if (TimeSpan.Compare(DateTime.Now.TimeOfDay, objTime) >= 0) { 
 } 
}