Uncover Hidden Hardware in Device Manager
When upgrading from VMWare ESX 3.5 -> 4.1, VM hardware versions changed from 4 to 7 which ended up orphaning Version 4 NICs. To get rid of these hiding NICs, run the following from a command prompt:
set devmgr_show_nonpresent_devices=1
devmgmt.msc

Refer to http://oreilly.com/pub/h/3105 for more info.