Thank you Edgar (and others) for the prompt and really helpful responses. This works wonderfully - the only change was I had to go into folder options and change the view setting because the first couple of times the file still had a hidden 'scr extension. I now have a fully working fish tank which is very restful but will have to forego the screen saver function (or read up on the per user account functions in Vista which I have not yet used). Major steps forward and I am impressed by your techinical skills - well done !