My apologies - I meant to include that we would only be doing this overnight. When we stop the process in the morning, are there any known 'side effects' that will affect the day-to-day running of our office PCs?

Also - if you wanted to render a 5 minute animation, say, over 1 week, but only at night - can you stop the rendering where its got to in the morning, and then resume it at night, each night?