s3nate... the gutmann method is enough for most things.... certainly should be more than adequate for what you want - however to quote the faqs from the link I pointed out earlier

Is the Gutmann method the best method?

A: No.

Most of the passes in the Gutmann wipe are designed to flip the bits in MFM/RLL encoded disks, which is an encoding that modern hard disks do not use.

In a followup to his paper, Gutmann said that it is unnecessary to run those passes because you cannot be reasonably certain about how a modern hard disk stores data on the platter. If the encoding is unknown, then writing random patterns is your best strategy.

In particular, Gutmann says that "in the time since this paper was published, some people have treated the 35-pass overwrite technique described in it more as a kind of voodoo incantation to banish evil spirits than the result of a technical analysis of drive encoding techniques. As a result, they advocate applying the voodoo to PRML and EPRML drives even though it will have no more effect than a simple scrubbing with random data... For any modern PRML/EPRML drive, a few passes of random scrubbing is the best you can do".

Read these papers by Peter Gutmann:
http://www.cs.auckland.ac.nz/~pgut00...ecure_del.html
http://www.cypherpunks.to/~peter/usenix01.pdf
and yes you will have to reformat the computer - DBAN wipes the partition table too - again this is in the FAQ (you might want to read it before using DBAN!)

ok as for your other questions... that could be a really long reply which I don't at the moment have time to write so... for a basic overview of file structure, read this

http://www.pcmech.com/show/harddrive/67/

You should also have a look here for more detailed explanations

http://www.ntfs.com/

as this may answer many of your questions - come back if it doesn't

Z