there are a bunch of prerequisites
that will need to be installed by hand , then there is the issue that a non paid for rhel5.1
has not had any of the recent security fixes installed ( they are in the rhn - the paid for access to )
are you prepared to install all of these by hand ?- some are in the default rhel but might be the wrong version
( in red at the bottom of the page )
http://rpm.pbone.net/index.php3/stat....i386.rpm.html
you might -- but with out the normal updates ?? it might work ?
fallow the centOS guide and use the cent updates repo and the cent epel
but you might kill the system if you are not VERY VERY VERY careful
-- but if you are going to use red hat
then pay for it or install and use CentOS