RHEL4 is old
you will not be able to install a new version on it
you might but not easily
also RHEL 4 was NOT free
is this an older version using "up2date"
or a newer version of 4 ( like 4.9 ) that has "yum" installed
seeing as you ARE paying for the Required EXTENDED Life support contract - for the continued support of 4 ( you do have a license ? )
ask red hat
libxpm.so.4 is in the old el4 "xorg-x11-libs"
use up2date or yum ( if installed)