"If you're not running a mail server, why have Sendmail start?
If you're not running a web server, why have Apache start? These
and many other linux services can be configured to not start at
boot up to save you time.
"In modern desktops (such as GNOME or KDE you will find on
distributions such as Red Hat Linux, Fedora, or Mandriva Linux) you
will find the Services tool in the main menu. GNOME, in particular,
houses this entry in the System|Administration menu. The image to
the left (click to show full-sized image) illustrates exactly where
you will find the Services utility."