How to view hidden disconnected devices in the device manager on Vista?

In case you ever need to uninstall a device that is no longer connected to your Windows Vista machine, here is how you enable viewing of these devices in the device manager:
Go to Control Panel
System
Advanced System Settings
Environment Variables
New ( user variables if just for you or system variables for all users of your computer )
In the Variable Name box type devmgr_show_nonpresent_devices and in the Variable Value type 1.
Then you need to OK it twice.

Now return to the Device Manager, click on view, and show hidden devices.
The Hidden/Disconnected devices will now be displayed in gray. Have fun right clicking and uninstalling.

Have Windows XP or earlier? Try this:
Go to c:\windows\system32, find cmd.exe, right click and choose “run as administrator”
In the command window which opens, type:
Set devmgr_show_nonpresent_devices=1 (press enter)
Devmgmt.msc (press enter)
In the device manager window which opens click View=>show hidden devices.