i have this on alot of forums if noone has an idea it might be a conflict with the versions i have and maybe ill have to get newest version of blender and python instead of the 2.49b one
the current export scripts don't support blender 2.5x yet so you will have to use 2.49b for now. also, i don't think blender supports python 2.6.5 -- i've used 2.6.2 with no problems, so you might try installing that instead.
you also need pyffi as well for importing/exporting NIF files.