In order for you to play ARMA: Combat Operations on Windows with minimal graphics settings, your computer must meet the following requirements
Supported OS:
Windows XP
Processor:
2 GHz or better Intel or AMD processor, or equivalent. Game is functional on, but currently not optimized for, Dual-core CPU's.
Memory:
512 MB of RAM
Graphics:
nVidia Geforce FX with 128 MB RAM & Pixel Shader 2.0 or better, ATI Radeon 9500 with 128 MB of RAM Pixel Shader 2.0 or better
DirectX Version:
DirectX 9.0c
Hard Drive:
3 GB of free space
Recommended:
Processor:
3 GHz or better Intel or AMD processor, or equivalent. Game is functional on, but currently not optimized for, Dual-core CPU's.
Memory:
1 GB of RAM
Graphics:
nVidia 6800 or better with at least 256 MB of onboard RAM, ATI X800 or better with at least 256 MB of onboard RAM