Thanks for your suggestions and thanks for your welcoming words.
poaalpina I tried the renaming but the encoding on the files is not recognised by any of the standard programs ie. Paint and image viewer.
drpino - thanks for putting me on to isobuster - seems like a pretty neat utility but it's no good for the conversion of files, it only seems to extract.
Also on a side note for this thread, while scanning through the cd I noticed the f.dat file sizes are all about 300kb which suggests to me the image quality will be a bit poo iaf and when I mange to convert them back. Anybody got any thoughts?