when backing up data on cd

[The Dad Fisherman]

If your using Re-Writables you can treat it like your Hard-Drive and keep writing, deleting and moving Data around. You do need a CDR-RW drive to use these.

As far as the backup erasing the data it all depends on how you have your back-up setup. It can over-write or it can append the data. If you just dragging and dropping folders then your overwriting whats there.