Ghost or Acronis are imaging software that copy your entire Hard drive as is, for example, when you first by a new computer or after a reformat, you can use these software's for like taking a snap picture of you system then save the image to another HDD internal or EXTERNAL, or BURN them to a CD/DVD, then if in the near future you have a problem with your computer all you do is put in the recovery disc or floppy and access the program, select the drive/disc where your image backup is and replace your existing drive with your back up one, no need to reformat & reload windows/software it will already be there. ( this can not work on occasions if you change some major hardware as you would need to make a new image of the system changes first).
If your just after saving some data or software then use Neros back up program or an external HDD or CD/DVD.