This is great - just what we have been looking for.

Have tried it on 1.3.7 test site and it has worked fine - apart from the IE problem. (In fact have just tried it on Safari and have the same problem)

Is there any way to tell in admin which customers have registered and which have not. Would be really interesting to know for sure whether mandatory registration really is a turn-off - I personally would much rather have no registration at all but simply a mechanism to check order status with email address and order number.