Do you know where can I download low poly, free, good quality trees? I need only about 6-7 models and I can't find anywhere anything good.

I don't know of any decent directories, but if you don't have a graphics artist friend, you can spend 10mins to figure out ngPlant (GNU GPL). It's pretty low-poly with LOD support, exports to .obj.

Example of Quality: e.g. http://povrayscrapbook.awardspace.com/

Ok thanks a lot. I think that this should help me