Rated 4 out of 5 stars

This addon isn't bad.And worked in the past. Sadly there's no development actually.If this addon does "not" work I can recommend this Greasmonkey Script: Google Preview Pane for Greasemonkey http://userscripts.org/scripts/show/50420
It is similar to Google Walker. But first you should try google walker.

This user has a previous review of this add-on.