How to make the game run faster? and lower mouse sensitivity

I set the game to low but ever time i get near the mother ship or asteroids i laggy out and the mouse is way way to sensitive but theirs no options to change that in the controls.
Is their a way to set the graphics detail to lower than low?

P4 2.4ghz
2gb ram
geforce 5600XT 256mb ram
Windows XP home