you could use blender which is free, but the interface is very odd compared to other software
but I highly recomend wings3d to get you started with modeling before you start animating, just to get used to 3d
I have never tried Animation Master but it is supposed to be very very easy and fast for animating, and it can model and do everything with the latest version I belive
Then there are the free versions of the big programs, Maya, XSI and 3DStudio Max. I'm a max user so I would recomend you try 3dviz I think it is called which is the free version of 3dsmax, has alot of features but also is kinda limited.
The free version of maya or was it xsi has a very anoying watermark on everything you do.
Of all those I would recomend you stay clear of Maya because its interface is wack compared to all the others. Blender also isnt recomended much because its interface is kinda good but its so vastly different from other 3d programs.
I would recomend 3dstudio max, xsi or lightwave and maybe animation master (if I knew more about it that is).