Installation:
For RHEL 5, CentOS 5 & Fedora
wget http://packages.sw.be/rpmforge-release/rpmforge-release-0.5.2-2.el5.rf.i386.rpm
rpm -ihv rpmforge-release*.rf.i386.rpm
For RHEL 6 and CentOS 6
wget http://packages.sw.be/rpmforge-release/rpmforge-release-0.5.2-2.el6.rf.i686.rpm
rpm -ihv rpmforge-release*.rf.i686.rpm
Then run: yum install htop