By the way -- something I've been curious about for some time, and I'll ask it here rather than the minimum skills topic just because this one is near the top at the moment.
I know that some versions of Lemmings allow you to solve "We all fall down" with just two builders, and I know what the trick is to that solution. So I can understand why it would require three on DOS. But how on earth do you come by 3 on the Fun version, 5 on Tricky, 7 on Taxing and 9 on Mayhem? I can't understand how a trick solution can be possible and yet not the same number for all four.....