winform

当前的屏幕除任务栏外的工作域大小
    this.Width = System.Windows.Forms.Screen.PrimaryScreen.WorkingArea.Width;
    this.Height = System.Windows.Forms.Screen.PrimaryScreen.WorkingArea.Height;

当前的屏幕包括任务栏的工作域大小
this.Width=System.Windows.Forms.Screen.PrimaryScreen.Bounds.Width;
this.Height=System.Windows.Forms.Screen.PrimaryScreen.Bounds.Height;

任务栏大小
this.Width=System.Windows.Forms.Screen.PrimaryScreen.Bounds.Width-System.Windows.Forms.Screen.PrimaryScreen.WorkingArea.Width;
this.Height=System.Windows.Forms.Screen.PrimaryScreen.Bounds.Height-System.Windows.Forms.Screen.PrimaryScreen.WorkingArea.Height;

winform实现全屏显示
WinForm:
this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;
this.WindowState = System.Windows.Forms.FormWindowState.Maximized;
this.TopMost = true;  

wpf

double width= SystemParameters.PrimaryScreenWidth;

double height = SystemParameters.PrimaryScreenHeight;

winrt

double width = CoreWindow.GetForCurrentThread().Bounds.Width;

double height = CoreWindow.GetForCurrentThread().Bounds.height;

官方的回复:http://social.msdn.microsoft.com/Forums/zh-CN/a376a37b-f7d6-4d05-aa8e-75768e2f12b7/win8?forum=winstoreappzhcn