Hi,
What should I do to make an existing CentOS (5.4) disc boot up on a new computer?
I just made on CentOS 5.3 installation on that machine, so I know the hardware is compatible.
Would it be enough to boot with a DVD in rescue mode, or boot with another hd, and install grub?
You might try to boot with the old hd right away. I did almost the same last weekend. Installed a new system for a friend on a virtual machine (using qemu) using a new disk and put the disk in his (old) machine (the machine wasn't available to me at the time of install) after installation.
If it doesn't boot (normally because the disk numbering is different) you can use a rescue DVD and grub to fix things (probably grub-install and maybe /etc/fstab for the /boot filesystem). Is the old hd using LVM and/or labels for filesystems ?
Regards,
Michel