Hello Dean!
The answer to your question is not a simple yes or no (is it ever?). I
support a couple of networks that run NT w/SP 3 and have decided
(perhaps wrongly, mind you) that the answer goes like this: system
changes refer to devices and services (go to Control Panel:
Start/Settings/Control Panel - you will find an icon for devices and
services). If you add or remove any device or service, you should then
reinstall SP3 (if possible, sometimes it's not and you just have to
cross your fingers..). I had a close and personal experience with not
doing this right (on a server no less!). I added RAS to the server,
rebooted and was greeted by the "blue screen of death". Nothing short
of reformatting and reinstalling the whole system could fix it. If you
change network protocols, reinstall SP 3. Note, however that some
hardware updates should not have SP 3 reinstalled after them. As an
example, there is a Zip fix (for ATAPI style Zip drives) that must be
installed after SP 3. If you reinstall SP 3 at a later date, the Zip
drive won't work (until you do the Zip fix again, and so on and so
on...). In Windows Magazine, February 1998, there is a list (p.276)
about this.
I hope this helps. Someone else might be more definite or
knowledgeable about this subject. These criteria have worked for me so
far.
Good luck!

Will Stephenson
mailto:[log in to unmask]

I understand 'SP3' should be re-applied following system changes -
does this
mean hardware/software/both ?