IMPORTANT:
my shader code uses an unflipped y in the normal map.. many dot3 converters flip the y in the normal automatically--including ATIs converter.. so basically if you use that make black the "highest" color and white the "lowest" so just invert your normal map(normally you think of white as the highest and black as the lowest). Some converters do have the option to change your y vector.. i suggest ORB (open render bump).