The Nandu version on the Firefox addon site only works through FF 1.5 and not 2.x. The author is currently rewriting the addon.
But... there is a link on the addon download page to a hacked version that DOES run on 2.x. I'm running it on 2.0.0.3.
Go here to download.
http://bundeenainfo.com/bundeena-nan...fox-2.0-6.html
Cheers.