the curent is RHEL 6.0
and it is NOT FREE ,nor is the current 5 series (RHEL5.6)
so use the PAID FOR support you DID BUY !!!
http://www.redhat.com/support/
you will need the username and password you set up when you bought RHEL
if you are not paying for RHEL then do not use it !!!
install CentOS 5.5
the best supported for 5.6 is "mplayer " and the gnome gui front end -" gnome-mplayer "
it is in third party repos
and you NEED a paid for license to install software