atlantis43 via WindowsKB.com u24690@uwe wrote:

Source for above statement (for RE-INSTALLING an OS) can be seen on
WD KB msg #1211, virtually verbatim!

"Western Digital provides software utilities that can erase all the data
on a hard drive. Writing zeros to a drive is recommended any time an
operating system is to be reinstalled on a boot drive or whenever a blank
drive is desired. "

Recommended maybe but by no means required. I have never had to write
zeroes to a hard drive before either first use or installing an operating
system and I've been working with PCs now for the best part of twenty five
years. Since I have never experienced problems that might require a low
level format I don't intend doing so now. g

Seagate in contrast say "Perform this "low-level-format" only if all other
POWERMAX tests have passed (or by direction of Seagate Technical Support)
and the hard drive is still not performing correctly."

Also, a top level IT acquaintance tells me (as I, with my limited PC
knowledge understand it) that there can frequently be 'duplicate'
files that are corrupted (perhaps due to malware, improper uninstall
procedures, etc.) that can be causing system malfunctions, and the
only way to solve the problem is to truly 'eliminate' all such files.

I'm sorry but for the greater part your friend is incorrect. Formatting a
hard disk is all that is required to remove a previous operating system.
It is very rarely necessary to write zeroes, this is normally only
required, and multiple times, when disposing of hard drives that
previously contained sensitive material so as to prevent its recovery
using specialist tools.

The only other time that I would contemplate performing a low level format
is if I was experiencing major read or write problems on a hard drive and
I had run the manufacturer's test utility such as Maxtor's PowerMax or
Seagate's SeaTools and the utility had made this recommendation.
--
Mike Maltby
MS-MVP Windows