It might be a good idea to toy around with software RAID on spare drive space, on a working system (ie: before you do the install, possibly on a root partition).
If you have spare space on both your drives, with RedHat installed already, follow the Linux Software RAID HowTo. I don't have time to link to it, but it will explain many or all of your questions. I didn't 'toy around' with my setup and jumped right into configuring RAID during my Slackware installation. It caused me some headaches, but Slackware gives you a root shell to run commands in during the installation process. I haven't worked with the version of RH you're talking about (only used RH9 for a while), but the installs tend to be menu driven. I think it might be hard to find RH specific RAID walkthroughs, hence the reason I suggest you play around with RAID on a working system so the install becomes easier. Depending on your Linux knowledge you might be able to move your drives from regular FS's to RAID, especially if you have space to backup your disks.
The basic steps are:
* make sure kernel has RAID and IDE controller support for your device
* create partitions with fdisk or whatever, they should be equal size
* flag the partitions as type 'fd' (compared to say, 82 or 83 for linux, linux swap)
* create an /etc/raidtab file (describing your RAID configuration)
* use the raidtools to build your device (i forget the names of the tools, but they're in the HowTo)
* Your RAID array will probably be called something like /dev/md
X where
X is 0, 1, 2, etc...
* Format your new RAID partition with a filesystem
* Use it
Good luck, the HowTo should be your bible for a while.
