I got an external drive, a 750 GB drive. The actual capacity of the drive is 698 GB. I have 678 Free. I only have one internal hard drive, with an actual capacity of 687 GB, and I have used 178 GB of my C drive. I have a 12 GB or so Recovery partition. Anyway, When I use widows backup to backup my computer, the backup size is 283.5 GB, which about 100 more GB than is taken on my drive? Why is this?