Irrlicht Engine

i want to know how can i disable mipmapping in a node

i want to make a collision between ~50 lowpoly nodes, and the camera.
the nodes are static and theres no movement.
what i dont understand is how to agroup the 50 nodes, create the octtree, and add it to the camera

hello.
i have this light.

scene::ILightSceneNode* luz = smgr->addLightSceneNode(0, core::vector3df(0,0,0),
video::SColorf(1.0f, 0.6f, 0.7f, 1.0f), 800.0f);

with wich function can i set it to another position with a vector3df date (like a camera)???

when i compile a program , and i select direct 3d 9.0c or 8.1 to use it , it says:
Microsoft windows xp professional service pack 3 <build 2600>
direct 3d driver was not compiled into this dll.try another one.
and it closes.
how can i do to use direct 3d???
(i have installed direct 3d 9.0c, and i ...