I once read something where it said you should ask the question "what if this is all gone tomorrow?" The effort you put into backups is determined by your response to that question. If you don't really care about anything on the drive, or it's all easily replaced, then you won't put much effort into backups.

The next question is "how could all this be gone tomorrow?" There are multitude ways, including theft, drive failure, fire, flood etc. It could be accidental file erasure, it could be making a change to a file and not being able to get the previous version back. For the longer term, it could be that your archives might no longer be readable due to the march of technology. All of these possibilities require similar but different answers. That's why you are reading about all these complicated methods of backup.

I use a mix of disk imaging, external drives and on-line backups (Jungle Disk in my case, but others are probably good) depending on which of my computers I'm protecting. As I start using each computer, I now do a disk image to give me a quick way to get up and running. All my computers get the on-line backup. My main computer also gets backed up to external drives. Since it has many gigabytes of photos on it, I wouldn't want to download them all if I needed to recover them. But, I like knowing they are in a secure spot off-site the day I take the pictures.