I have been running a laptop as my primary display and a 17" CRT as my secondary display.
They duplicated each other exactly until I went into Display Properties the Settings,on this screen,(I run Win XP Home)it offers a facility to represent the physical way in which my screens are arranged which I did,ie 1 above 2 below.
Now I have lost the desktop icons task,bar etc from monitor 2.
However it is still possible to move the mouse pointer to the position of the secondary screen as shown in Settings and it appears as if on the primary screen but with no Desktop icons.
I have tried to overlay the two screens but it does not allow that.