Have you considered an exorcism?..
TR
Do you have a tutorial ? 
Well, there are these wiki pages…
Hmmm,… Worth a shot I suppose. 
Btw, pm’d you with a thought about the model.
Just working my way through your info here, Tarot, and I’m struggling to understand what I’ve downloaded with the 5 extra models of various sizes" link. What I’ve downloaded seems to be a gif that doesn’t do anything. Can you give me an idea of how to use it?
Don’t know how that happened. I somehow posted the wrong link. Edited it now. To save you having to scroll back there, this is the proper link.
TR
Thanks, Tarot. Sorry for the delay in replying but I’ve been trying to come to terms with the mind bender that is Blender !
The link now works and I have the code for five new sizes of models as I understand it. Can these just be used as before with the 1X1 example or are there any more “hidden” steps I should be aware of ?
I’m assuming this will allow a larger image to be used for the texture from my POV ?
They can. No hidden steps but the texture name (it is right next to the keyword bitmap in the model) does not need to be similar to the other things you change (but it still needs to match the image’s filename). I did it that way to simplify the steps needed.
Regarding these 5 models. Now it may just be me but I tailor my texture size to the size of the model. NwN (all versions) works to a metre scale. That being the case I tend to use the following little formula. Take the dimensions of the model in centimetres and round them up to the nearest power of 2 (e.g. a 1m x 0.5m model is 100 x 50 centimetres and I would round that up to 128 x 64 pixels for the texture image size. Works for me anyway.
Regarding those tutorial links that @TheBarbarian posted. I double checked and one ebook that I regard as essential for custom content work is not actually on that page. You really should get the Custom Content Guide V3.0. While somewhat dated (and practically all the links included in it no longer work) it is still packed with useful information.
TR