change terrain built in shaders

Hi i need some help with changing the terrain shaders in to diffuse ore something because i got a old GPU(Pshader 1.4) so the terrain looks very blurry and lame and i cant affort right now an upgrade. I know that i need to overwrite them but thats all, i dont know how to edit the shaders so any help would be very helpfull . thanks in advance:D

there is nothing you can change. The "shader" (its not a shader) used there is already the optimum for your hardware. It uses a baked texture that stretches over the whole terrain and has the various layers baked in, because it can not blend in realtime. Baked textures just lose a massive amount of detail (because the shader based drawing has a visible texture detail thats worlds higher than the actual texture on the terrain, but with the baked the actual texture size is exactly what you get to see). Thats exactly what you see.

Without realtime pixel shader composition thats the "best of the feelings" you can get I fear.