" How do I start the Profile Manager?
The Profile Manager is used to manage multiple profiles. To start the Profile Manager on Windows, follow these steps:
1. Close Firefox completely ( select File > Exit from the menu).
2. Select Start > All Programs > Mozilla Firefox > Profile Manager from the Windows Start menu.
On other operating systems, start Firefox with the the -profilemanager switch, e.g. . /firefox -profilemanager
Once started, you are able to add, remove or rename profiles. Note that the profile manager may be removed in newer versions of Firefox, which will force you to use command line switches instead of the graphical interface."
http://texturizer.net/firefox/faq.html