Thanks all for information so far, in particular the recommendations which actually describe why the programme is worth installing.
In the past certain Mudcatters have asked the question - "If you want to know technical computer stuff, why ask on a folk forum?" but as far as I am concerned, I get good unbiased advice from people who have good judgement and a wide experience.
I'll check out the programmes mentioned and if necessary check back with you.
Quack!
Geoff.