Switching motherboard: troubleshooting?

[Rich Braun]

I'm trying to overhaul a server and have run into a weird boot problem.  Can't
readily find the solution online--other than suggestions that perhaps I should
switch to another distro, but I don't want to give up quite yet because I
spent a lot of time on this installation.

Basically I bought a new hard drive, downloaded SUSE 10.0 from the gatech
site, and used my desktop PC's motherboard to get everything loaded and
configured.

Then I tried plugging the hard drive (actually, two drives, RAID1) into my
file server's motherboard.  No luck:  I get "Waiting for device /dev/hda2 to
appear" and it gives up trying to mount the root fs, dumping me into a
primitive shell.  The IDE interface doesn't show up in /proc/devices.

SUSE's rescue CD is quite useless.  Amazingly so, in fact:  it doesn't even
have a copy of fdisk!  If you try running the installation diagnostic, it
fails to recognize a root fs in anything other than a top-level partition
(forget RAID, forget lvm).

However one quirk about the rescue CD is this:  if I boot it up in rescue
mode, the kernel will recognize my IDE bus and I can manually mount the
filesystems.  So far as I can tell, it's the *same* 2.6 kernel image as the
one previously installed on the hard drive.

I'm stumped, after tinkering a lot with command lines to GRUB.  Where might I
turn to come up with ideas, other than to trash this setup and switch to Red
Hat?  The file-server's motherboard has an old BIOS but I have no reason to
believe this is the problem.

-rich