BuddyPress.org

Correct. It does do almost all of the work with a modified CSS. Except the header.gif and a few other minor changes. Plus, by pulling down the header.php file and putting it into the Fishbook folder, then you’re overriding that file too so that you can customize it for your needs.

You could just change the core header.php file, but then when you upgrade BP you’ll have to remember to change the header.php file again since it will get overwritten.