A friend of mine has a 40G hard drive FULL of MP3s.  It is all in a VFAT file 
system, you know, Windows 95 or newer, because he was running Windows when he 
ripped and collected the songs.  Well, the drive is now connected to a Linux 
box but VFAT does not provide good permission administration under Linux so 
he wants to convert it to ext2 or some other Linux friendly file system.

Is there a utility to convert the file system "on the fly" so he does not 
have to move the data to other media and copy it back again?  I know large 
hard drives are cheap now but he doesn't want to worry about doing the whole 
dump-change original file system by formatting-dump back thing.  Plus he 
would rather not spend any money.

Alan