Anyone understand GRUB?

[Michael Hipp]

My system boots off a RAID1 SCSI but has a potload of IDE disks after that. 
I'm trying to figure out what to put in /boot/grub/menu.lst so it will boot 
faithfully from either SCSI disk.

Here's what I currently have (somewhat leftover from when I had only IDE disks):

title           Ubuntu, kernel 2.6.15-27-server SCSI Disk1
root            (hd0,0)
kernel          /vmlinuz-2.6.15-27-server  md=0,/dev/sda1,/dev/sdb1
                 md=1,/dev/sda2,/dev/sdb2 md=2,/dev/sda3,/dev/sdb3
                 md=3,/dev/hda1,/dev/hdc1
                 root=/dev/md1 ro quiet splash
initrd          /initrd.img-2.6.15-27-server
savedefault
boot

That 'kernel' line is all one line but I wrapped it here for readability sake. 
Here's what the md devices mean:

   md0  /boot
   md1  /(root)
   md2  swap
   md3  bulk data storage (not need for booting)

The 'root' line is what bugs me. I think hd0 properly refers to sda since I 
have BIOS set to boot SCSI first. (How to verify that?) But why does it boot 
properly using the '0' partition (that's /boot). And what do I put in to allow 
me to boot from sdb (automatically, hopefully) - note that there are 2 
scenarios here: a) sda has disappeared, b) sda exists but is empty?

The grub docs aren't much help: 
http://www.gnu.org/software/grub/manual/html_node/index.html

Confused, as always,
Michael