I've got a P4 2.66GHz and 512MB of RAM. I have a Ge 4400Ti (128MB). I run ay 1280x1024 (my LCD only supports 4 screen sizes, next down is 1024x768, too small for me).
Some time ago Pyro or Skuzzy (somebody from HTC) let me know that the best texture size for me at these settings is 215. I'm going to be getting some more ram, adding 1GB, and wanted to know how much I could bump that texture resolution without screwing myself over.
Is the texture size based on your video card capabilities, or on your system ram?
EDIT: Also, are the range and detail sliders (in-game options) based on vid card capabilities (vertexes/shapes etc) or on how much memory you have (to store those shapes)?
I get really good FPS most of the time, so I don't mind losing a little.