Thanks to Paul and Fred for the response re RAID drives.I'm looking for the best way to have a backup drive that can be immediately substituted for the C: drive should that fail. But I want to make sure that a virus that attacks all the drives that it can find on my computer will not see the one I'm using for backup. I was thinking the easiest way is to "remove" (turn the power off of) the backup drive. I guess that means doing disk-imaging not mirroring.Harry Binswanger hb@xxxxxxxx