Awe... awe... AWE!
Your mac expert is certainly not one, and I am sorry for you. When I was managing hundreds of macs, I used radmind, and I could have easily scaled it to tens of thousands. (given appropriate funding)
'She refuses to use MS Entourage' She is actually correct there, but only because Entourage has this nasty habit on OSX of trashing its own database. *shakes fist*. We pushed people to mail because we did not have an exchange server, and we were sick of supporting it.
Radmind is definitely its own thing, and it would scare most people, as it asks a lot of the user. For small (up to 100-200 maybe) computers, apple remote desktop and a task server would work fairly well. It is a lot closer to SMS, and it is all graphical.
Apple's group policy like thing in open directory is rather good, but it doesn't do all the things that group policy does. It also does a lot of stuff that group policy cannot, so I really don't know if one could be called better.