on NVIDIA GeForce2 MX/MX 400:
on ATI Radeon 9800 Pro:
Well, the terrain material requires pixel shaders to work which the Geforce2 does not have. If you want to support the Geforce2, you will have to fall back to a simpler material, most likely one with only a single texture for the whole terrain. You can generate one from your splatting layout with SplattingManager::createBaseTexture (obviously though you cannot use a Geforce2 to create the splatting layout in the first place because the generation of that base texture can hardly be done in realtime).
There is a possibility to do alpha splatting without pixel shaders, but it's not very good. You will need coverage maps with only a single channel, so for each texture to splat you would need the splat texture and one coverage map. All in all, you can expect to use maybe two, three different splatting textures in a whole, the Geforce2 would not be able to handle more. You can read about how to setup a material for this here: http://www.ogre3d.org/wiki/index.php/Ma