On Cent OS 4 the very last screen says REBOOT. Before click that do CTRL-ALT_F2 and get a prompt. then enter the following commands.
This will allow the software raid arrays to boot.
grub find /boot/grub/stage1 device (hd0) /dev/hda root (hd0,0) setup (hd0)
This is easier the setting up mdXXX commands after boot.
Jerry