FreeFileSync

FreeFileSync is an Open Source application that will let you synchronize two folders and make sure they always have the same content to have one of them as backup. If you only have one HD, this kind of programs will not be really useful but if you have a removable disk, FreeFileSync will be really useful because it allows you to have two folders synchronized in order to have a backup. FreeFileSync is very easy to use. You only have to choose the origin folder and the destination one and the program will do the rest. It automatically checks the origin folder and, in case it detects any change, it will copy the modified files automatically.