If we are talking about windws there is no hope in "you know what" that files will be written contiguous, that is the biggest flaw in windows
I think that only linux writes files contiguous on the harddrive.
Both ext2 and ReiserFS provide features such as user-level security and more efficient use of disk space, so that defragmentation tools, although they do exist for ext2 at least, are rarely needed.
Windows is just very sloppy with harddisk space