Highest settings: http://abload.de/img/1high6orvz.jpg
I had to play with lowest settings on a laptop with a intel graphics media accelerator a few years back. Man, was so happy when I built myself a computer.
Mud: The Game.
I had a similar experience. I played on lowest on a 11 year old Acer Notebook for a while while my computer was hooped. I still had a blast with it, but wow, Tripwire is not afraid of turning the texture sampling down.