Hi Sara,
We had a similar issue to deal with, in light of an internal security incident involving security privilege escalation in our Active Directory.
Our admins were under the impression that whatever the ACL Editor (and the “Effective Permissions” tab) showed them resultant access correctly.
Turned out to be not quite true. We never realized that in order to accurately get this info, we had to take interesect every permission in the ACL, consider inheritance, denies, nested groups etc. - we'd been struggling with this stuff for a long time now.
So we asked around for solutions that could help us and a Microsoft consultant pointed us to one of their security partners, Paramount Defenses Inc, that has developed an Active Directory delegated access auditing tool called Gold Finger - http://www.paramountdefenses.com/goldfinger.php
It turned out to be very easy and helpful – it took a few minutes to download, install, and run and it immediately showed us who was delegated what access in our domain.
We did come across a few other cheaper tools, such as from Scriptlogic and others, but they all just seemed to show us the security permissions, still leaving us to manually do all the work to figure out the resultant access, so they really weren't useful in this regard.
Gold Finger has saved us a lot of time and effort, and allowed us to easily audit and lockdown access in our Active Directory, which we have started taking seriously after that incident.
So I would recommend trying it out. By the way, I think it can print reports as well, so you might in fact be able to fulfill your delegated access reporting requirements in time for your auditors.
Good luck.
Sam