Check out 6_pac's advice here
http://www.gnutellaforums.com/297206-post2.html

The location of the Themes folder in that post is for Win XP. I don't use Vista, but I'm pretty sure that that your Themes folder will be in this location...
C:\Users\your username\AppData\Roaming\LimeWire\Themes

You'll need to show hidden files & folders to be able to find that Themes folder, the thread below explains how to do that.
http://www.gnutellaforums.com/genera...der-vista.html