Aviation Week had a good article on this subject this week, comparing the record of the AH64 and the AH-1 in the desert.
To summarise: US Army AH-64s were used in isolation - they went tooling off alone into the night and flew into a large area of ground full of Iraqis firing wildly into the air at any noise or light. The result was that most of them got poked full of holes such that they needed to be mended before they could go out again, but only one was lost. This indicates that they are in fact (for helicopters) pretty well armoured and survivable.
The USMC used their AH-1s as part of a combined arms team and hardly got the paint scratched.
So the only real conclusion that you can draw is that the US Army need to study modern manoeuvre warfare a bit harder.
Or maybe (and perhaps I'm being a bit cynical here) the next time the AH-64 Bn cmdr says "Gee ... leave that to me and my boys, we can do anything !" his boss needs to administer a reality check.