ok if the file was a binary file .. or a song .. what would it do for it in this case? how will it be filled by garbage?
In the end, its all 1's and 0's, so it doesn't matter what kind of file it is - it will still fill it with garbage. But beware- forensic people are smart. They can actually use nice, big magnets to find previous overwrites (or HD formats) - kind of like x-rays and studying overpaintings. cool, eh? What does that tell you? If you have sensitive data, better keep it on paper and burn it. Or make sure you go into a great hassle removing your data (preferably exposing to Huge magnets, followed by melting...)