thanks. I think the other guys I'm working with have a better handle on this than me anyway -- leave them to it.. ;]

I started looking at this batch render; my other problems include setting up directories, and the fact that there's some left over animation in the scene - I just wanted to render a still. I deleted the keyframes but still ended up with a load of files all over my images folder.

more homework needed on this I think - at least I know batch is the way to go. thanks