Here is a bare-bones solution for those that want to spend literally no money for their backup solutions. This two-step method will especially work well with your external drive, regardless of the version of Windows that you run:
1. A simple batch file that uses xxcopy (
http://www.xxcopy.com) will backup any types of files and/or directories. It may take 20 minutes to create the command that works for you the best (there are a LOT of switches) but once you have it, you will not have to touch it again.
2. A free scheduler such as the one found at
http://www.splinterware.com to run your batch file in the wee hours of the morning or whenever.
This works beautifully for any drive, external or internal, including USB drives. The one place I have had trouble with this method is attempting to use it to backup large files to DVD's using "Drive Letter Access" software. I definitely don't recommend it for that.