Thanks Mick for the advice.
Reason for query :-
We have an older PC which the children use. They can all be responsible for installing stuff or changing settings, which cause problems and crashes (both of the twins at 6 years old have absolutely no fear of installing games from discs thay have found - we find them, playing all sorts of stuff on the 'puter).
Windows is also a pain when different programmes start to interact - usually because the Microsloth programmes deliberately sabotage anything produced by a rival company and cause crashes or blue-screen errors.
I am using a programme (Acronis O-S Selector) which allows me to clone my operating system and then run (one at a time) different customised clones.
I am trying to set it up so the Kids have one clone they can use, and if they trash it, I can restore it from independent backups, or if necessary, just delete the clone and start afresh.
I also decided that I would have a clone set up for e.g. Music applications, one for Photo manipulation, one for general office work. That way, I don't have too many conflicting programes on any one clone, and it should be easier to prevent of identify software clashes. Part of the idea is to have as little duplication as possible on each clone.
The programme works by hiding the inactive "clone" systems from the active clone. They are however all stored on the same partition, so take up space (It hides the "Wimndows" sytem folder and the "Programmes" folder for the spare clones so that the active clone cannot detect them).
Obviously, each clone takes up space on the drive partition, so I am looking to find out what I can delete from each clone to reduce wasting disc space, bur still allow the customised clones to do what I want them to do.

I would also appreciate thoughts on what other Windows options and junk I can remove from the clone operating systems - "Desktop Themes" and the like. How far can I strip Windows down and still have a working system?

By the way, the PC I am working on had Win ME installed as an OEM setup - I do not have any actual Windows system installation discs, just the "Restore it to the way it was when you bought it" discs.

Quack!
Geoff.