Can you attach blend?
Edit: found it after I read your whole post
First your textures in material are incorrectly set.
Your normal map uses generated coordinates for mapping, should use uv (you know this, right?)
You need to enable “normal map” under image sampling so blender knows this texture is a normal map.
You need to disable color and enable normal from the influence panel.
You can’t use AO map for the bump map, it will not just look right. Also, if you want to use a texture as a bump map you need to do these two things for the texture. From the influence panel enable normal, and for bump mapping space choose texture space.
And if that texture will only have that one object then I recommend to make that texture 128x1024, there is alot of wasted texture space if you want to leave it 1024x1024
Your highpoly also needs some love but that is another story, if you want to hear it then just ask me in this thread and I will clarify a bit.