Today I decided to see if I could export some of my models to Morrowind so I installed PyFFi and the Nif Scripts but they don't show up in Blender. I use Blender 2.5 so I of course downloaded the 2.5x scripts and I installed them to my .blender/scripts folder.
Does anyone else use Blender 2.5? Is it even possible to use the nif scripts with that version of Blender?
Just out of curiosity, why don't you use the Blender 2.49b that is "stable"?
ABout the Nif Script, you may try to report the issue here
http://niftools.sourceforge.net/forum/viewforum.php?f=13&sid=39dca218a2fb51d144b3321940d4108f