Data destruction

[Elmer E. Dow]

Greetings:

This post is not RH specific, but given the experience level of the list 
participants, it seems like the likely place to seek input on this subject. 
If there's a more appropiate place to post, please let me know.

I'm researching available data destruction programs that I could use for 
getting rid of an organization's financial info, etc. before 
donating/disposing/reusing an old computer. Have any of you used the 
following programs? Good or bad experience? Any words of advice?

Darik's Boot & Nuke (http://dban.sourceforge.net/) can be installed on a 
diskette or CD. It appears to be a one-function live distro for the paranoid. 
Just stick it in the drive and hit enter and it'll overwrite everything. The 
caution to clearly label the disk seems justified.

Secure Delete (http://freshmeat.net/projects/securedelete/?topic_id=43) is a 
bit more versatile: "Secure Delete is a set of three utilities to perform the 
following: secure deletion of files, secure overwriting of the unused 
diskspace on the harddisk, and secure overwriting and cleaning of the swap 
filesystem." 

I also found a program called Wipe (http://wipe.sourceforge.net/). It's the 
one that's commonly included on live forensic or security distros (see 
http://www.frozentech.com/content/livecd.php). However, the site states 
"There are some low level issues that must be taken into consideration. One 
of these is that there must be some sort of write barrier between passes. 
Wipe uses fdatasync(2) (or fsync(2)) as a write barrier, or if fsync(2) isn't 
available, the file is opened with the O_DSYNC or O_SYNC flag. For wipe to be 
effective, each pass must be completely written. To ensure this, the drive 
must support some form of a write barrier, write cache flush, or write cache 
disabling."

Can someone with more knowledge than I tell this greenhorn just what the above 
paragraph means and how one could be sure that the machine would do this? If 
it needs fsync, then shouldn't it simply be run from a live distro that could 
provide that? Am I correct in assuming that each of these programs would wipe 
all partitions of a disk regardless of the file system used (ext. 2, ext. 3, 
FAT32, NTFS, etc.)?

Elmer