There seems to be some confusion on your end, but I'm not sure from where.
In any case, all the nVidia cards I've tried to date most certainly DO anti-alias the character models' edges, and the ATI cards do not.
I can post screenshots tonight if you are really having a problem following this.
(In any case, I have a hard time believing they would leave as much polygon clipping in the game as they did if it was really all just prerendered. Take a look at this screenshot
from Gamesdomain, for example)