Server Backups

Someone here mentioned a while back that they used a 2nd hard drive on their server and used Norton's Ghost to copy one hard drive to the other....as a means of backuping up the server.

My question is: would you use an "internal" or "external" hard drive?

thanks,
DBlack

External would be my choice -- that way should the server go down it would be easier to get at the backed up data. I know it's a simplistic answer to what's probably a more technical question.
--Dan