Hehehe, the GeForce4MX's have no pixel or vertex shader support (before anyone replies saying yes it supports vertex shader - it's SOFTWARE.).
UT2003 uses some basic pixel shaders on the ground, for precision and speed above all else. They don't actually change the texture or add any effects, just improve precision and speed. So yes, it will look better on any PS-supporting card... especially Radeons - the 8500/9000/9100/9200 lines support a very high dynamic range when using pixel shaders 1.4 (which GeForce4Ti doesn't even support).