There are two types of back up - a clone, and an image. The clone is an exact copy, with programmes all in, that is designrd to come in to use if your hard drive fails. An image,is a back up but also a copy of your system and can be made so it is incremental - only the extras since the last back up are added. A normal copy is ok for data such as music, documents etc but will not let you replace system programmes. There may be free software but most people think Acronis True Image (about £30) is well worth buying. I have version 11 but I think there is version 2009 about now. A clon or image shoul ideally be on another drive (USB HD or similar). You could put a normal back up on a new partition on your disc.