I don't know. I know with Fear 2, 12 1024x768, it barely got an average of 26 fps. I know AC2 is all DX9 (no DX10 like the first one).
If you go to http://www.yougamers.com/, you can test to see if it will work. I can't remember if they have AC2 up there yet, but it will test take into account your GPU and CPU type and will give you a fairly good assessment as to whether or not your PC can handle the game based on the games minimum and recommended settings.