Just a bit of praise for a piece of software that I have been using. I would say its probably the best backup software that I have used!
Its called Rsync, and its primarily an open source linux based software, but you can get windows based version here
You can set it up to back up via SSH across a network, or like me just to another Hard Drive in your Computer. When you install it you run the Client copy, and the server copy and set up what you want to back up/when and where to.
The beauty of this program is it installs as a service, so the software doesn’t have to be running, and uses next to no resources, so you don't even know its running! It pretty much syncs the two directories that you have selected, so if you add, say, some photos to your target directory, and delete a couple at the same time, when it is scheduled to back up it mimics these actions on the target directory. Meaning that if one of your HDD's crashes, you have a perfect back up of your source directory! You can also go as far to sync it with an ext HDD once a month to store offsite! (my plans)
The main reason why im giving this praise, is that as I said its not a resource hog! I had to configure my firewall a little, and tweak the settings in the program a bit but once its up and running its great!
Anyways just thought I'd let you guys know