To those using SuperDuper, it appears to have some bugs in the newest update version (2.6.2) and at least Snow Leopard. It will not allow multiple scheduled backups, either by time, or by when drives are connected. SD will only backup the first drive, it ignores the rest of the drives. It will then sometimes post an error message and freeze the computer, you can not force quit SD, (attempting to do so is moot, nothing happens) and must do a hard shut down. I've emailed to Shirtpocket about this but have gotten no reply. For now I recommend you stick with your current version until this issue is resolved.