In order for you to play Killing Floor on Linux with minimal graphics settings, your computer must meet the following requirements
Operating System:
Ubuntu 12.04 LTS, fully updated
Processor (CPU):
1.2 GHZ or Equivalent
Memory (RAM):
1 GB RAM
Graphics Card:
Nvidia, ATI, or Intel GPU with hardware-accelerated drivers
Hard Drive:
2 GB free hard drive space
In order to play Killing Floor on Linux with maximum graphics settings, you need a computer with a configuration no worse than the following
Operating System:
Ubuntu 12.04 LTS, fully updated
Processor (CPU):
2.4 GHZ or Equivalent
Memory (RAM):
2 GB RAM
Graphics Card:
Nvidia, ATI, or Intel GPU with hardware-accelerated drivers
Hard Drive:
2 GB free hard drive space