Cleaning

["Alex Kirk" <alex@schnarff.com>]

I'd like to go about cleaning my hard drive, so that my free space is 
absolutely empty. In other words, I know that even if I delete files from my 
system, remnants of them are still physically on my drive; I also know that 
it's possible to clean those off, and that's what I want to do now. 

I believe this can be done with dd, but I'm not sure how to go about it. Any 
pointers you can give would be very helpful. 

Thanks,
Alex Kirk