The hardware requirements shown on the website.....hahaha.....this will never be enough to play ArmA 3 with 40 - 50 FPS.......Never.....:(
Look at ArmA 2 or OA....
But I think the only chance is if the Game Engine is really optimized für multicore Cpu´s.
It´s better to have an core i7 (one of big cpu´´s), 4 GB or 8 GB RAM, and the biggest Graphiccard you can get in 2012 when the game will be released.
Assasine