I'll be brave and differ with everyone.
The main advantage of a backup hard drive is that if your main computer's hard drive is corrupted, you can get EVERYTHING, not just your photos back.
Here's what I would do:
1) Use Disk Utility (in the utilities folder of Applications folder) and select the back-up hard drive's name NOT your main computer, and erase it. Do extended HFS but not with journaling on.
2) Download Carbon Copy Cloner (do a google search) and down load it and install it on your computer and put it in the Applications folder.
3) Clone your entire computer's drive. In the preferences of Carbon Copy Cloner you should check the "repair the permissions" and possibly make it bootable. (It would probably be bootable on your back-up drive even if you didn't select to bootable square.
4) Make your target disk your back-up disk, and clone it all.
5) Repair the permissions on your back-up hard drive with disk utility.
You will now have a total back-up of your computer's hard drive on your back up hard drive.
6) Send the creator of Carbon Copy Cloner (CCC) a donation--it's worth it.
If your computer dies, use your system start up CD to launch CCC on your back-up drive and clone your back-up to your computer.
Look into this on other forums to make sure what I'm telling you is well grounded.
John VL
I just received my 160gb external hard drive (SimpleTech
SimpleDrive). I connected the drive to my iMac by firewire and it
shows on my desktop. This is my first external hard drive, so I
have some very dumb questions. I tried to save a few photos on the
external drive and nothing happens. Do I need to format the
external hard drive (I am using Panther)? What is the best way to
use an external hard drive? I will be adding a Powerbook G4. Can I
share the external hard drive with my iMac?
I apologize for these "beginner" questions.