I spotted this gem in http://support.microsoft.com/kb/825826:

Check for nonpresent, ghosted, or hidden network adapters

To uninstall the ghosted network adapter from the registry, complete these steps:

1. Click Start, click Run, type cmd.exe, and then press ENTER.
2. Type set devmgr_show_nonpresent_devices=1, and then press ENTER.
3. Type Start DEVMGMT.MSC, and then press ENTER.
4. Click View, and then click Show Hidden Devices.
5. Expand the Network adapters tree.
6. Right-click the dimmed network adapter, and then click Uninstall.

It’s one of those things I’ve often wondered about – so simple when you know how…