I'm sorry I've been away from this for a few days but it maybe deserves a few replies:
Maroman, thanks. When I open that window, I don't get the middle of the three versions that you get. So, I'm not sure what is different about my system. Like you I am a little sad that we still can't completely do without Microsoft.
leenie, thanks to you too. That is the one I was referring to in my second post above. As I said then, unfortunately it doesn't support graphs and charts in spreadsheets and that is quite important to me. However, for those for whom that is not a problem, in my experience, file import/export compatibility with MSO formats is very good indeed.