What should I upgrade to be able to play Arma III with my current rig?
in general its CPU and HDD --> SDD
your rig should do fine ( with the info we currently have)
btw. very hard to tell atm...

Nothing. Its perfectly enough I would say. Unless you wanna extremely high settings.
anims
Well I will buy an SSD for sure in the comming months . So this upgrade is 100% sure.
Nice to hear though that my current rig could deal with ARMA III in a good way![]()
My PC handle BF3 pretty well all maxed out at 1680x1050. Occasionally during large explosions it will drop to 20 frame rates, then goes right back up. ArmA 2 still gets to 23-24 frame rates in grassy areas with nothing going on.ArmA 2 also gets my GPU hotter.
Simply put, ArmA 3 will probably require a much faster PC than BF3 does.
That doesn't necessarily mean that ArmA2's graphics are better than BF3's. There is something called optimization and memory leaks and stuff. Because BF3 is pretty demanding with it's effects and stuff. For graphics that don't look as intensive as BF3's, ArmA 2's graphics shouldn't be as demanding as they are. However BF3 does their graphics and effects/particles and stuff, ArmA 3 should take an example from that. If BIS can rework the effects, even if they are more like MW3's 2D effects (hopefully not though), then ArmA 3 may not be THAT demanding.
My advice is to wait until about a month before release, since all the technology you'd want and need will probably be out by then, and prices for already available products will probably have dropped.
Not talking about map sizes. What makes ArmA lag is not just the maps. It can be an increased view distance, or upped graphics settings, or a lot of particle effects going on, like a lot of smoke or something, which is what causes the most lag for me. With BF3 and all the destruction and explosions, and effects heavy stuff that goes on, it still runs better than ArmA. ArmA 2's effects look simple compared to BF3's. And I can run BF3 on the highest setting at 1920x1080 resolution, playing 32x32 player servers. I experience lag with ArmA with less AI than that. Maybe it's just my system, but that shouldn't be the case.