If you are really going to backup correctly it should be to an external drive.I use Acronis and also all my files are on a different drive to my OS drive+plus I have images of the three PC's I have in the house on a NAS drive.
I also use Sky drive to back up all my documents and pics,
So a belt and braces man myself.
Cannot help you with windows backup or Norton. But use whatever you find easiest and works for you.