minimum: 2.8GHz, 512mb Ram,Geforce6
for high details: 3-4GHz, 1Gb Ram, Nvidia 6800GT/ultra or 7800GT/GTX SLI
Dual-core Processor use: Multi-Threading is supported and should provide much better performance.
64 Bit version available with better textures
Renderers: Shader-3.0, Fallback-Mode for Shader 2.0 maybe a dx8 renderer.
HDR: yes
physics: Novodex-Physik-Engine.
Ageias PhysX Processor supported.
Don't know if this is official or not, but Beyond Unreal says the german site http://www.extreme-players.de/ is claiming to have read it in a german magazine with a creditable Epic Games source.