Hello Ian_33,
Arma 3 is a game that requires more processing power from the CPU.
Your current system will run Arma 3.
Running at lowest settings could yield some very playable frame rates. Changing or disabling more demanding settings like PIP (Picture-in-picture) and Anti-aliasing would help out. For multiplayer servers, you may have to reduce settings slightly. Arma 3 tends to drop frames when trying to handle lots of players on larger servers. In the settings menu of the game, it will show the FPS you are getting with the current settings, adjusting and finding a frame rate that works for you is the best way to do it.
An upgrade would help out, but if you are okay with running at lower settings (I had to do this for a while before I got myself a new system, it's not that bad) than your system will do it.
Hopefully this helps,
-Nick