If you're in Max and using the scanline renderer, try using Hammersly anti-aliasing at .5 or 1.0, or if you're using Mental Ray, try setting the anti-aliasing it to 1 and 4, or 4 and 16, etc. instead of the default 1/4 and 1/4 (IIRC). Also, if you downscale the normal map, perhaps run it through Nvidia filter to normalize…