Just because you aren't a "professional" yet doesn't really make much difference. :black:
I am a student myself and I have a PowerBook. I chose it over an iBook because I knew I was going to be using the entire Adobe CS2 suite, the Macromedia Studio 8 suite, After Effects, Final Cut Pro, DVD Pro and other high-end professional apps. The iBook would crumble under the weight of those programs so I opted for the professional machine to go with the professional apps. Since you too, will be using professional level apps, you will require some more substance from a machine.
The iMac would be fine if it weren't for Maya. Would the iMac handle Maya?... sure it would. Would it handle it well is another story.
3D apps really need a higher-end graphics card to run at their peak performance. There is no option to upgrade the iMac's graphics and the 128 MB might strain under Maya (depending on what you do with it). For that reason, I suggested getting the Mac Pro since it has better graphics and the ability to upgrade later on, should you so desire.