Windows keeps a Device Manager entry for every piece of
hardware that's ever been recognized by the system, regardless
of whether it is currently present in the machine or was even
set up correctly in the first place. The "View Hidden Devices"
option in Device Manager won't show you these "residual"
drivers. You can force it to show you everything by going to
My Computer Properties, the Advanced tab, Environment
Variables, and adding a new system variable with the name
"DEVMGR_SHOW_NONPRESENT_DEVICES" and a value of 1. Now opening
Device Manager and choosing "Show Hidden Devices" really will
show you everything. Standard practice at the factory is to
use a single image and just move it from model to model,
letting it plug and play all the new hardware along the way.
This leaves you with an impressive list of hardware still in
the Device Manager, but no longer in the system. You also see
this to a lesser degree when you restore a system from an
image you created for backup purposes. These "residual"
drivers can sometimes cause all kinds of weirdness and are
best removed by right-clicking on their entry in the Device
Manager and choosing "uninstall".

This works on Windows 2000/XP (and I assume Server 2003,
though I haven't tried it). Anyone running a factory loaded
Compaq or Dell will be amazed at the amount of junk left over
from this process.
Jon Pickle

Thanks, Jon. Indeed, Windows has a thing about hanging on to ghost
entries in Device Manager and also in the Registry. (This is one of the
reasons why Registries inflate so much over time.) A little judicious
ghostbusting lets your PC run cleaner and leaner!