upgrading rh7.3 to 9.0

Older versions of Red Hat Linux have been moved to the following location:

ftp://archive.download.redhat.com/pub/redhat/linux/

rpm --rebuilddb

rpm -Uvh http://linux.duke.edu/projects/yum/download/2.0/yum-2.0.4-1.noarch.rpm
Retrieving http://linux.duke.edu/projects/yum/download/2.0/yum-2.0.4-1.noarch.rpm
error: failed dependencies:
libxml2-python is needed by yum-2.0.4-1
rpm >= 0:4.1.1 is needed by yum-2.0.4-1
so i skip this step

wget http://archive.download.redhat.com/pub/redhat/linux/9/en/os/i386/RedHat/RPMS/redhat-release-9-3.i386.rpm
rpm -Uvhr edhat-release-9-3.i386.rpm
yum upgrade