thanks for the detailed response.
I did all the above but sh4.exe wouldn't work in the copied folder, it just kept throwing up a dialogue box but I can't remember what the error was as I deleted the copied folder. All I had done was opened the original SH4 using the SH4.exe file and opened the first of the training missions to check that the game worked before making the copy. Is this likely to be the cause of the error as if it is I'll delete the Steam installation and reinstall.
Thanks once again for the response.