I'd like to say thanks to all the guys who have contributed to this thread, there is a lot of really good info in it.
I have spent the last three evenings fiddling with my settings to try and get this great game running at a decent FPS.
My system is as follows:-
P4 3ghz, Running at 3.3ghz
2GB DDR400 Corsair
ATI X1950 Pro (AGP) - Catalyst 7.3
Asus P4C800E-Deluxe Mobo
X-Fi
450W PSU
Windows XP Pro SP2
Latest drivers for everything, constantly defragged using Diskeeper (every time the Screensaver kicks in, it defrags), Windows Pagefile on it's own logical drive (not the 'c' drive)
I dropped all my settings and my res to 1024x768, ran ArmaMark and got a score of 954!!!
Changed my res up to my native Windows res of 1280x1024 and got an ArmaMark score of around 1300.
Although better, this still seems really poor for my hardware, and I have seen guys with similar or lower spec machines getting better scores. I just don't understand why.
Am I missing something crucial?