I teach 3D and web design in college. I use a PC because 3D Max works on a PC (not Mac) and pc's are generally cheaper for the power it gives you vs buying a mac that can cost the same amount of a used cars. I like macs too, and if 3D max worked natively on Mac I might be more mac centric.
As a teacher in an art school, almost all the computers around are Macs. Which is a skewed version of the real world. So I'm also happy to teach one of the few classes on a PC to let art students know that in the work place they might encounter a non mac environment. And if they want to just do art, there is an alternative to spending 1000's of dollars to get started -- they can spend 100's and get started too.
But, being in a Mac centric place has its drawbacks... viruses. The PCs aren't guarded as well as the Macs. And I caught a virus from doing my job as a teacher -- collecting student homework and bring it home to grade. Occupational hazard
When I'm not teaching, I'm programming interactive stuff (flash, C#, etc).
If you have any 3D questions or Flash questions I'd be happy to help out, I'm in the information sharing business by trade
stu rain