I am needing to use RHEL 5.1 on a variety of machines at different times. Does the install compile a special kernel suited for the specific machine, or is it a general purpose kernel with lots of modules and auto-detecting hardware at boot? I'm wondering if it's reasonable to simply use the same hard drive in a variety of machines instead of constantly installing RHEL.

Does it have to be RHEL 5.1? If not, you could probably just use any old Live CD and keep whatever other files you need on a thumb drive.

Or it looks like there's a CentOS Live CD. CentOS is a near perfect clone of RHEL.

Yes, unfortunately it must. I'm doing lots of hardware testing with linuxes, so it needs to be specific flavours and versions. Just trying to make the process more efficient.

Well, to your original question, I doubt the kernel is specifically built other than by architecture (i.e. i386, AMD64, PPC, etc). So you might be able to get away with it. The problem might be more in the driver setup in that the driver is setup at installation, then when you move the drive, things need to be reconfigured. Maybe RHEL has some tools to help you reconfigure the drivers, or maybe they'll auto reconfigure. But if it installed on a machine with an nvidia card then you moved it to a machine with an ati card, it might object until you reconfigure xorg.

That makes sense. Xorg is easy enough to configure. Guess I'll find it out if anything else requires special configuration. Thanks!