Just a reference for anyone else reading this... you can just as easily change root's password with out the use of a LiveCD.
reboot the box
at the boot loader do the following:
type 'e' to edit the default kernel line
then 'e' again on the line that starts with 'kernel'
add 'init=/bin/bash' to the end of the 'kernel' line
type 'b' to boot it
once you're at a /bin/bash prompt...
remount the filesystem read/write (will be ro when bin/bash'ing)
# mount -o remount,rw /
then change the passwd
# passwd root
remount the filesystem read/only (keep things clean)
# mount -o remount,ro /
CTR-ALT-DELETE (though this will result in a kernel panic most likely)
reboot the system and you should be good to go.
This however will not work if you've locked down the boot loader and have misplaced that password as well.