How to Speed up a Mac OS X 10.5 computer by disabling dock reflections
In this clip, you'll learn how to turn off dock reflections on an Apple computer running the Leopard operating system. With a little know-how, it's easy. So easy, in fact, that this video guide can offer a complete overview of the process in a matter of a few minutes. For more information, including a complete demonstration and detailed, step-by-step instructions, take a look.
For reference, the lines mentioned in the video are as follows:
defaults write com.apple.dock no-glass -boolean YESkillall Dock