This is different than Centos 5, you have two services btu they are called "smb" and "nmb".
You need to enable and start "nmb" in order for your samba server to be listed.
chkconfig nmb on; chkconfig smb on
service nmb start;service smb start
centos, samba, server, workgroupthis, btu, quot, smb, nmb, enable, listed, chkconfig,