Maya3D and 3D Studio Max are far most 2 top programms, but both are targetted for some specific purposes, as I've found Maya more oriented towards characters, and 3D Studio Max towards buildings, models etc. but as well character animation and rendering can be done well in 3D Studio max. as I personelly didnt touched Maya, but did character rigging and animation in 3D Studio max.
but stilll I beleive Maya is more towards Character animation/shading/rendering, as Spiderman, Shrek was made in Maya. at the same time Final Fantasy was I think made in 3D Studio Max.
other programs are as well needed, as learning any one of thee wont help competely, you'll have to learn programs like Macromedia DIrector, Adobe After Effects, etc etc.
latest thing out of Maya I have seen was that ATi's Ruby Demo (you must have seen it) it has character animation more than other thngs.
check out websites:
(for 3D Studio Max)
3D studio Max's can be further extended to using other softares like combustion (for complex animation and rendering).
what ever you do, dont ever thingk that in a 3D animation, every thing is created in 3D software, actually it isnt, like to qoute example of SHrek, ok its skeleton is created in maya, but skin/clothings must have been made using soem other 2D software, like CorelDRAW, Adobe Illustrator, Adobe Photshop etc etc, these clothings are then wrapped around the original Character.
any more confusions/Questions, ask.
whatever you choose, in both cases, you'll have to have a good OpenGL accelerated card (nVidia Quadro or ATI FireGL), normal cards though have OpenGL, but these workstation cards are specifically designed for 3D. thats why these cards costs around 2000$, as compared to best of the Video Game/Movie Player card at 400-450$.