There exists two handy GUI applications that you can install from the applications menu:
Search for StartUp-Manager and BootUp-Manager and install the one which is interesting for you.
StartUp Managerconfigures some settings for grub and splash screens (colors of grub screen, if messages will be shown during booting, ...).
BootUp Manageris a graphical tool to allow easy configuration of init services in user and system runlevels, as far as changing Start/Stop services priority.
See also this post about this tool.
Install instructions from shell
sudo aptitude install startupmanager bumor click these links: Install Startup Manager, install BootUp Manager.