API Call

1.

I am having a handle of a window. Can i use it for closing ,hiding, showing etc. regarding to that particuar form/window.

2.
Can I know the processes which is running in background with the help of apis and if want I can close them accordingly.

3.
I am not getting the handle of the window that is come when we press ctlr+alt+del

1. yes - ShowWindow(), TerminateWindow() etc. take this handle

2. yes

3. In the real OSes (NT, 200, XP) The task manager window lives in its own protected desktop (see ApiDesktop class for info) which you cannot muck around with...sorry.