I use Memeo backup. This program came with an external hard drive I bought several years ago and I have been quite happy with it. It backs up designated files/folders as they are changed in real time. It is not a resource hog - I don't notice it running in the background. Restoring using Memeo will recreate the file structure, but the files themselves are not hashed so you can copy the backup directly if needed. Multiple backup versions can be kept, but this can quickly turn into a very backup set. I've used the program several times when transferring data between computers.
