Hi
I find power karaoke CDG Ripper to be the best:
http://www.powerkaraoke.com/src/prod_powercdgburner.php
Its easy to use and produces good results. You need to make sure that your drive or drives can read ( and write if you want to burn back to disc) the CDG format.
This site has a good list of drives and what they can do:
http://www.dartpro.com/support/devices.asp#CDGRecorders
I use a Plextor External USB drive and that has been great.
Hope the above helps.
Cheers
Paul