If you are going to do that, you might as well just update the OS to RH 9 via yum/apt.
But if you want the newer packages, I'd just upgrade the OS. I did a RH 8.0
to RH 9 upgrade via apt-get the other day. Was painless, and only downtime
was the reboot to load the new kernel in.
R.Parr, RHCE Temporal Arts Seattle