There are several help files which explain how to achieve that goal. Here are a couple of them: Profiles - Where Firefox stores your bookmarks, passwords and other user data which explains what they contain and Managing Profiles which illustrates how to move data from one profile to another.

Each of these contain links to other relevant topics.

Xircal,

Thanks for the link. I have used these exact same methods before when transferring and moving profiles when working with various versions of firefox 3.xx.xx. But when using these instructions to move and copy profile data from my current 3.6.17 version to the new 4.0 version it does not seem to work properly. Am I missing something in all of this because of the new 4.0 version?

Maybe you missed this link in the above articles? Back up and restore information in Firefox profiles

Click the link to "Restoring to a different location".