If you have custom panels, extensions and other Fireworks assets you would like to move from one machine to another, just copy the appropriate sub-folders under the location mentioned below into the new machine:
WINDOWS XP:
<OS Drive>:\Documents and Settings\<username>\Application Data\Adobe\Fireworks CS5\
Vista/Win 7:
<OS Drive>:\Users\yourname\AppData\Roaming\Adobe\Fireworks CS5\
MACINTOSH:
\Users\<username>\Library\Application Support\Adobe\Fireworks CS5\
Once the files from the corresponding sub-folders have been copied, restart Fireworks on the new machine and you will see the same state of fireworks as previous system.

Thanks, Sarthak!
Just a quick note, though – some extensions install themselves in the program installation folders, not in the settings and preferences folders. Also, I think the Guides and Transform panel extensions install an additional folder called “Shared” in a separate locate on Windows XP, and without that that “Shared” folder they do not work.
Hope this helps!