If you are imaging or backing up the entire C: drive, then those backup files on the C: drive are getting backed up or included in each new image or backup also, so it each new backup is larger in size. TI has an option to exclude certain files or file types from the image, so you could set it to exclude .tib files. However, an image or backup of the C: drive isn't much use if you store it on the C: drive. When the C: drive fails, your backup is also gone. Backups of the C: drive should be stored on a different drive and/or on DVDs, with one copy off-site (in case your house burns down or the computer is stolen).