UUID grub fstab

I wanted to migrate my data to a SATA disk from an IDE disk on an Ubuntu 7.10 system. In the past, I have simply tarred the contents of the partitions to the new disk, updated fstab and bootloader configs, reinstalled the MBR, and rebooted. However, in this instance, since the disk was laid out the same, I didn't really need to update partition info in grub config and fstab. If I had, I would have noticed that Ubuntu uses UUIDs for fstab and the grub config for identifying partitions. So I found myself with a system unable to get past the bootloader. My 'quick' fix was to use an Ubuntu CD in rescue mode and change /etc/fstab and /boot/grub/menu.lst to the 'old' style of /dev/sda1 etc. I then acquainted myself with the concept of UUID ('apropos UUID') plus some web searches. I found that you can find the UUID of a partition by running 'vol_id -u ', e.g., 'vol_id -u /dev/sda1'. I then copied this to fstab and menu.lst.

I think that UUID is handy way of doing things, in that it is possible to attach another disk to a machine without worrying whether it will change the order of things (e.g., by becoming the first scsi disk, and your system disk becomes the second disk, whilst all the fstab and grub entries point to the first still). It is still a slight mystery to me why the BIOS is able to boot from the second disk without modification though. Also, I am not sure why grub, when configured with (hd0) after adding a new disk which then becomes primary, isn't bothered. Maybe because this is just in the initial setup, and the bootloader is installed there anyway.