In order to install oracle 11g u need to have 10GB of space + 3 GB ram + good processor . Otherwise your machine will run very slow. I will always prefer 11g , but hardware configuration is not good then u better install 10g
CentOS is not a supported distro - supported OS versions are listed in the Linux Install guides for your specific version of Oracle at http://docs.oracle.com
Others have attempted to use CentOS, some successfully. Any issues arising out of the install or use of the software on this OS, you will have to troubleshoot on your own.
Is there a reason you cannot use a supported OS ?