What's dangerous about that? Considering how cheap hard drives
are, it makes perfect sense. If you buy two $60 drives every four
years, that's $30 a year -- 60 cents a week. That is cheap protection,
and even cheaper peace-of-mind.

I haven't counted for a while, but I think I have about 50 customers
(those that call for work more than once per year) involving about 150
machines. Pre-emptive drive replacement has totally prevented drive
failures, and the attendent all night restore session. However, it
also has produced in a rather motly collection of "used" drives,
mostly 10 thru 40GBytes. They still work, but being past their prime,
they're not suitable for use in a customers machine. I use them for
backups, but that's also risky if I run into one of those failures
that isn't dependent on running the drive. With 4 years runtime on
these drives, they're sure to fail within about 2-3 years of normal
use. I sell a few, with the usual disclaimer and non-warranty, but
after having to deal with a few irate former friends, I just stockpile
them. Anything where S.M.A.R.T. shows a climbing error rate, gets
recycled.

How does one access the S.M.A.R.T. data? (You don't need to explain, just
point.)

I was planning on making my initial installation of XP on a lightly used
drive I'd put a "vanilla" installation of 2000 on, so I could de-crap my
regular drive of malware. (I don't know how I was able to boot them
simultaneously without screwing up things, but I did.) Perhaps I'll just buy
a new drive right off the bat, and when XP is fully installed, get a second
drive.