I don't really use automatic backup method, because I have a few computers in the network that I go back and forth. I used a Windows based syncing program to sync all computers of Documents, Music, Photos, etc., but it went corrupt. So I'm not gonna use that method anymore. I don't like automatic backups because I need to access the only specific files from an external hard drive. When I modify a file and put it into an external hard drive, "Date Modified" section does not change. Which worries me that the drive is corrupt. (The drive was originally used on a Windows machine.) Before I go any further in backup my files, I want to format it based on a Mac since it's primary OS. How should I go about this? Is there a different format for Mac and Windows drives? I want to start from scratch. I still need to use it between two OSs.