I had exactly the same problem with Slackware 10.0
Most probably the boot kernel doesn't support your sata controller or sata disks at all.
I have no experience with RHEL but with slackware you have to choose among many different kernels before the actual setup starts.
If you have a choice list all the available kernels of the boot CD and choose one that supports sata disks.
Alternatively you can install on an old ATA disk, then compile a new kernel with sata support directly into the kernel (NOT as a module) and then migrate the system to the sata disk (I have no idea how this happens
). You could even try another distro!