Pretty sure you mean the little geen Droids (Andy)..
You need to use
Launcher Pro I believe , also download the icons and change stock icons with "
Better Cut," or a similar program.
There's detailed instructions at this post as well as links to download the droids (instructions are for Droid X but should work with any android phone I believe):
http://androidforums.com/tips-tricks-droid-x/115618-how-custom-icons-your-droid-x.html
good luck & happy customizing!