Thanks for the suggestions
I will definitely give both a try today.
I also had a look at the MicroAngelo software and it sounds like it might do the trick but we're not making icons in the same sense that most of these programs intend so it is a bit difficult to find all that we're looking for in one program.
A lot of the icon generating software that I've tried can't replicate the icon hundreds of times and re-name the files sequentially. Or they only allow you to save it as a .ico and not a .gif.