From the look of it, I can say your normal map has inverted Y values. This is THE MOST ANNOYING THING EVER with normal mapping.. !!!!

ok, sorry, this is one of my pet peeves..I will explain:

there are two 'standards' for normal maps, the ATI standard with 'inverted Y' and the Nvidia standrard non-inverted Y. In practice, this has nothing to do with how hardware works or Nvida vs ATI, but simply how you write your shader. The upshot of this is, it is a completely trivial thing that causes all sorts of confusion. Basically, most of the shaders you will find on this forum that use normal mapping use the NON-inverted Y method for normal maps. You can usually specify this in whatever program you use to make the normal map.