So true, support contract for Maya is same as a new low-end Mac Pro. And thats only piece of software I have to deal with.
But to date, were using Maya on a Boxx 8400 Windows 7 system.
I generally like Adobe/FCS/Avid/Protools on the Mac Pro side.
The Boxx is a great machine, but it isn't an inexpensive one either. I prefer the ability to move back and forth between OSX and Windows 7 at will, and the Mac Pro can do that.
Autodesk is really a first class supporter of the Mac. AutoCAD is coming to the Mac which is good news to Architects and Civil engineers and there are a bunch of apps that you are familiar that have or will be getting OSX treatment. If Inventor goes OSX, I would be out $8K plus another $2K a year, but I believe in supporting vendors that support OSX native apps (Siemens NX is an X11 app and price like Pro/engineer).
You have a cool sandbox to play in...