How can I view devices that are installed but not connected on my Windows XP or Windows 2000 computer?

Open the command prompt (go to Start, Run, and type cmd.exe).

Create a devmgr_show_nonpresent_devices environment variable and set the variable to 1 by typing

 C:>set devmgr_show_nonpresent_devices = 1 

Start Device Manager by typing

 C:>start devmgmt.msc 

Within Device Manager, select "Show hidden devices" from the View menu.