From HostThyself

Often you will want to have have certain service running as soon as the system boots up. Or you may want to stop some services from starting up automatically.

In CentOS this starting or stopping a service at boot time can be done using chkconfig.

To turn off pcmcia, use

chkconfig pcmcia off

To turn off httpd, use

chkconfig httpd on

To check what is running, use

chkconfig --list