Windows XP or Windows 7 and file system NTFS ---> Is it possible - or maybe even very likely - that there's still unallocated data of a single file left on my PC after overwriting it at least three times? And if yes, is this unallocated data enough data for a professional person to recover more or less the entire file? Someone told me overwriting free space is the only 100% safe method to destroy unallocated data? Is this true? Thanks in advance for your answer(s).