Compared to modern bleeding edge uber gaming PCs, Aces High is pretty thrifty on resources and doesnt need a terrible uber gaming PC to run it at its best.
I got a modest Athlon 64 3200+ (Skt 754) which is pretty old-skool these days, Radeon X800Pro 256Meg, 1.5 Gig generic budget RAM. Windows XP, Audigy II sound card.
I run at 1280x1024, 1024 Textures/High-res pack, graphic details all at maximum, 6x AA, 4xAF, Textures and Mipmaps are all on full qaulity and i limit framerates to 60FPS, and it seldomly drops below 40.
The only thing i can improve on is the resolution, but i only have a 19" monitor, and thats about the right resolution for me.
I dont think theres much need to go all-out if AH is all that you play. YMMV.