Hi
I started out trying to use Disk Cleanup, but it didn't show Windows.old as one of the things that it could remove?
After trying Ubuntu and logging in, in Administrator mode, (both of which wouldn't do it) I finally found a tutorial about changing the security settings for the folder.
It was fairly involved with a number of steps, but I finally got rid of it.
I've just spent some time removing everything else I could from the drive (my software is all installed elsewhere) and now I have a little breathing space.
When I do the real install I'll leave a bit more room.
Mike