I have a bottom end spec
4Gb Ram - XPsp3 - GTS250 (512mb) - Dual Core E5400 2,7Ghz
Screen Res 1280x768
Nvidia control panel set to default (no triple buffering, etc)
VideoSettings Low except for Model Detail/Effects which are medium. Trees, grass, roads, shadows all off.
I have a minor artifact that suddenly shows up all the time (ringed in the pic below) and can be seen in the other screenshots. Nothing major and runs well enough untill the fixes and upgraded CPU/GFX card are fitted.
Combat over Sea is acceptable and, as can be seen, fps drops as ac get closer and debris starts to fly off. These are momentary drops and still acceptable. Switch mirrors 'off' and FPS increases but not necessary most of the time.