[CentOS] RHEL5 Linux with default Cluster is not Installed

[Balaji]

Dear All,
 
   I have installed RHEL5 Linux Installation and I have selected all 
packages but the cluster packages are not displayed at package selection 
Menu
   After Installation Completed Successfully i have verified cluster is 
installed default and I findout the cluster packages are not installed 
default linux installation

  Can any one help me how to install the cluster packages with default 
linux installation
  Otherwise send me Cluster Installation Procedure after linux 
installation is over

Regards
-S.Balaji