Many thanks for all your very interesting replies, they provide plenty of food for thought.I'm obviously starting to consider my options when I come to replacing my trusty old,but still functioning, old pc.
Based on a number of factors,I would probably go for FSX but if I did so,I would still hang on to FS9 until such time that I was happy with it,particularly when it comes to installing some my existing favourite Classic British aircraft in FSX.
I suppose one incentive to move on would be the opportunity to install some different scenery and airports.
In terms of hardware the impression that I get is that a reasonable spec would suffice but I might sound out some opinions from around here.
A change would involve something of a learning curve anyway because it would probably involve Windows 10.
Once again thanks for the advice.

EricT