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OK having checked, it is not clear if doing this means I can load the program I have so it works. There are links to XP compatible software, including my program, but on clicking it, it is for the updated software by yahoo (for which you have to pay too) so this brings me back to my original question - any reasons anyone can think of why I could not or should not go back a system on my lappy.
BTW, the lappy is only used for surfing and storage.