I know that I have to use Blender 2.49 to import and export Blender-files to the nif-format, I read about it in the forums. My picture of the simple iron plate is taken in nifskope .
Blender development will not stop; Niftools, Nifscripts and Nifskope will be developed further, too. Skyrim will still use the nif-format, so sooner or later it will be possible to import and export nif-files to and from Blender 2.5. So why as a newbie should I start learning a complete new program using an old version? If I were a beginner at the CS I'd not start with CS 1.0 but use CS 1.2 from the beginning.
Moreover I meanwhile discovered a series of video tutorials for Blender 2.5 on the internet (http://www.agenzas-brothers.de/blender_lernen/tutorials.php) and the best of it is, they are in my own language German, so they will be much easier for me to understand than the english tutorials for Blender 2.49.
Thank you all for your kind comments. You made me pick up learning Blender once again.
But it will be a long way, let's see where the road takes me and whether the journey will be a short or long one.