Chris, I am sure you would agree that there are many great tools for producing music on Mac OS. As far as the Cubase vs Nuendo debate, I would add that although Nuendo 1.5.2 is amazingly innovative (Supports 5.1 Mix) and although it is a great program (I was on the Beta Test team for Nuendo on PC), is was in it's infancy when OS 9 was shelved; it was a complete re-write from scratch (as compared to VST), so it is very buggy under Mac 0S 9 (I have also lost projects/time with then never ending Nuendo crashes).
Cubase VST 5 is so much more solid since it was the final version with a long history on Mac OS. Cubase "VST" was released first on the mac, was developed for mac, and was improved from 1996 thru 2001. Its 5 year run as a Virtual Studio got better and better as PowerMacs got faster. It may not have surround sound (like Nuendo), but it wins hands down in the stability & features department.