Whether you're on an i7 or a Core Duo it is still an Intel and Mac OS is just an interface between your hardware and the piece of software you're trying to run, so much so that this piece of software is always presented with the same resources and the same methods to use them (just like driving a car, you've always got a steering wheel and pedals that are presented identically from car to car). If Nuendo works on an Intel Mac, it works on all Intel Macs until they dramatically change of architecture. That was for the geeky bit.
Now, about Nuendo itself. Rather, I would imagine your problem to be related to your specific install (if you do a clean install you will see more clearly what options you have left, I don't know how painful the process can be with Nuendo...). Before you do that, just make sure all OMF's are unusable and that it's not a problem with one particular OMF file.
Also I don't know if you've already come across this video, but OMF's seem to be problematic with Nuendo 4.