Many services are required to run all the time however many can be safely turned off for both security reasons as running unnecessary services opens more doors into your computer, but also for performance reasons. It may not make much difference but your computer should boot slightly faster the less services it has to start on boot.
This post explains how to start/stop the services and how to control which services start automatically at boot time for Ubuntu System
The scripts located in /etc/init.d are part of the bootup sequence of every Debian-like distro. Very often Ubuntu's documentation and guides have suggested - in order to deactivate init scripts - to change the permissions of the scripts in /etc/init.d, making them non-executable. This will have the following consequences:
* You'll get an error message at boot time (to avoid it you need to patch all the scripts);
* You are breaking the logical chain stated in debian-policy concerning runlevel configuration.
If the logic of a debian-like system boot up sequence is not very clear and familiar to you, you should not play with symlinks, permissions, etc. In order to avoid messing up your system, Boot-Up Manager will automate all of your configuration in a nice and clean graphical interface.
Open up "Ubuntu Software Center" : Application >> Ubuntu Software Center and find for package "BootUp-Manager" and install it.
After successful installation go to : System >> Administration >> BootUp-Manager
Bootup-Manager got a very clean and simple interface through which you can start/stop or Disable the services in Ubuntu Linux System.