Hi all,
I have solved the issue, I believe you use a command like this in fstab,
/dev/hdc1 /mnt/backup ext3 pamconsole,exec,noauto 0 0
I think this doesn't check the device exists when the pc starts up so if it is not there it won't stop the sme box from booting.
If anyone else knows a better way to add the backup drive to fstab ie: knows the command better than I and can point out a better way, then it would be nice to hear from them.