There's An(other) App For That Rated 5 out of 5 stars

If this happens to become unsupported and obsolete, there's a very similar add-on called the Element Hiding Helper for AdBlock Plus. It also stores rules for permanent removal of page elements, and it also uses a WYSIWYG approach and has already been updated for Firefox 4.

Also, NEVER download and install an unverified XPI file from an unknown source (e.g.! You could be walking right into a malware trap. How do you know what's been done to that XPI file? If all you need is a version bump, there are automated tools, like MR Tech Toolkit, that can force compatibility with new FF versions. Of course things might break doing it, so caveat emptor/YMMV/etc.

This review is for a previous version of the add-on (  This user has a previous review of this add-on.