If you have a need for continuity in your operating system, then you will notice that the System menu contains no icons like the Applications and Places menus. Here’s how to enable the icons so that the System menu looks like the others.
1. Go to the main menu. Select Applications, mouseover Accessories and select Terminal.
2. Execute the following terminal command:
gconftool-2 --type Boolean --set /desktop/gnome/interface/menus_have_icons True
3. Close the terminal window and go back to your System menu.
Instead of seeing this:
you will get this: