Can you locate the start up items for the original web cam and disable them?
To identify what loads when you boot use Autoruns (freeware from Microsoft).
http://technet.microsoft.com/en-us/sysinternals/bb963902
With Autoruns you can uncheck an item, which disables it from starting, or you can right click an item and then delete it. If you uncheck you can recheck to re-enable the item. It is a much safer approach than editing the Registry and better than using msconfig.
A useful feature of the programme is that you can right click an item and select Search Online to get information about the item selected.