In Xp and Vista it was easy to retrieve the display device ID (I.E. \\.\Display1, \\.\Display2, etc). The returned deviced ID's matched the display numbers as depicted on screens with the "identify" button....where a big '1' and '2' would appear on the monitors if clicked.
In Windows 7, this...
bug report
device id
displayidentificationdisplay numbers
enumdisplaydevices
getmonitorinfo
graphics
hardware
multi monitor
randomness
reliability
screen resolution
tech support
troubleshooting
user issue
video card
vista
windows 7